In The Beginning
In the beginning, God created the Heavens and the Earth (Genesis 1:1). God created Mankind in His image. We are image bearers of God. Genesis 1:28-30 says that God's original intention, in His perfect creation, was for human beings to rule over Creation as God's agents, under God's authority.
But then Adam and Eve chose to rule in their own authority. God's only rule was "You may surely eat of every tree of the garden, but of the tree of the knowledge of good and evil you shall not eat, for in the day that you eat of it you shall surely die." (Genesis 2:16). Or in other words, "Let me (God) be the arbiter of Good and Evil, because I know the difference, and if you become evil, you will die. And I don't want that, so let me handle it". But Adam and Eve were deceived by Satan and disobeyed, choosing to be their own arbiters of what was good or bad.
Unfortunately since that day, human beings have been ruling creation under their own authority, and redefining good and bad as they see fit. It can be hard for some of us to admit we've screwed up. Unfortunately while we may be following humanity's rules, it is not humanity who is the final judge. Like a hot stove that will burn you regardless of how you feel about it, Good and Evil remain the same no matter how human try to redefine it, and humans have moved things around so much that they have earned themselves death without even realizing it
Death
God is the giver of life. We have life because He gave it to us (John 1:3-4). However, God can not abide imperfection. As a perfect being, anything less is an anathema to Him. Since humans have tried to redefine Good and Evil as they see fit, they have moved things around to the point that our perception no longer aligns with reality. We are no longer perfect. Thus God can not abide us, and if He removes Himself, then as a result, we no longer have Life.
There is no such thing as "good enough" we either are perfect, or we are not. Additionally, perfection is not attainable once lost. As Temporal beings, we can not go back in time and fix past mistakes, thus future perfection can only meet the standard. It can not exceed it or atone for the past.
Salvation
There is, however, a way. For some reason, God loves us enough that He still wants us to be with Him. But there was still the problem of imperfection and the resulting consequence. Instead of starting over as soon as Adam and Eve sinned, and trying again on version 2.0, He put in motion a 6000 year plan to redeem humanity, and restore creation.
Sin requires Death (Romans 6:23). My death can atone for my sin, but then I would be dead, which defeats the purpose. So there needed to be a death that had no sin to atone for. For several thousand years, people engaged in animal sacrifice. Each year they would sacrifice a perfect lamb or kid (goat) to atone for the previous year. Obviously this is not sustainable.
So God sent His son Jesus to earth, to live a perfect life, and then die as a final sacrifice. Since Jesus had no sin of His own, He could pay for our sin. Then God raised Him from the dead, proving that Death had no power of Jesus. And therein lies our salvation.
When God created the world, He laid down the rules based on His nature as a perfect Being. Humans broke the rules and so lost the "prize". But Jesus came along, followed the rules, "won the game" per se. And now, as a result, instead of having to win the game, Jesus offers to credit His victory as ours. Instead of having to be perfect, we just have to acknowledge Jesus and accept His gift.
ABCs of Salvation
There is a trite, yet succinct way of understanding the logistics of salvation.
A - Admit you are a sinner
There are some people that won't put on a coat because they won't admit they are cold. Likewise, to accept Jesus's salvation, we have to admit we are in need of it. Repentance is having a change of heart, mind, and direction. It is saying that you know you are a sinner, and you don't want to be anymore.
B - Believe in your heart that Jesus Christ was raised from the dead
If Christ was not raised from the dead, our faith would be useless (1 Corinthians 15:14). It is the resurrection that proves it all. It proves Jesus paid the price, it proves the sacrifice was enough, and it proves that He has power over death, so that when the time comes, He can raise us up too.
C - Call upon the name of the Lord
This is trusting with all of your heart that Jesus Christ is who he said he was. Namely, the Son of God, the second member of the Trinity. That one day every single person who ever lived will bend their knee and confess with their mouth that Jesus Christ is Lord, the Lord of Lords and the King of Kings.
In a sentence these three steps are repenting, accepting Jesus as your Savior, and accepting Him as your Lord.
So what does this all mean?
Over the millennia, there has been a certain amount of dramatizing, embellishing, and simplification of the ideas of Heaven and Hell (actually, many cycles of this resulting in a strange game of telephone). But if you get into the theology of it all, it boils down to this. Heaven is where God, the source of all love, joy, peace, and comfort, lives. And Hell is where God is not. Logically, therefore, Hell will have no love, joy, peace, or comfort.
When all is said and done, once everyone has made up their minds, He will separate those who want to be with Him into Heaven, and those who don't want to be with Him into Hell. Salvation is not just about an afterlife. One day, God is going to remake the world according to His original design. And the plan that Adam and Eve derailed, will be back in place. Salvation gains you entrance to that kingdom, and it is available to all. But God will not force it, He will respect the decision you make. He has reduced the price of admission from perfection, to a simple choice. Do you want to spend eternity with God, and are you willing to accept His sovereignty? One day, everyone will bow down, but will you do it willingly or resentfully?
Additional Resources
Tim Mackie - What the Bible, Jesus, and Christianity are all about