Everything else on this site rests on one claim: that Jesus Christ is who he said he is. If that is not settled for you, start here.
We are not basically fine
Most of us grade ourselves on a curve. We measure our lives against people we consider worse and conclude we are doing reasonably well. Scripture will not allow that comparison. It measures us against God himself, and by that standard all have sinned and fall short of the glory of God (Romans 3:23). Not only the obvious failures, but the pride, the resentment, and the quiet indifference towards the God who made us.
This matters because sin is not a technicality. It is a broken relationship with the one person we cannot live without, and it carries a real consequence.
God did what we could not
Here is the heart of it. God did not wait for us to improve. Christ died for us while we were still sinners (Romans 5:8). Jesus lived the life we have failed to live and died the death we deserved. Three days later he rose, and in rising he broke the hold of death itself.
This is why Christians speak of grace. Not a reward for the respectable, but a rescue for people who cannot save themselves. For by grace you have been saved through faith, and this is not your own doing; it is the gift of God (Ephesians 2:8).
What this asks of you
Two things, and they belong together. Repentance, which is turning from going your own way. And faith, which is trusting Christ rather than yourself. This is not a formula to recite. It is a genuine change of direction, and it is the work of a lifetime.
It costs something. Jesus was honest about that and never recruited anyone under false pretences. But he was equally clear that nothing you give up compares with what you gain.
If you want to take a step
Speak to God honestly. Admit what is true about you. Ask him for the mercy he has already held out. There are no special words required.
Then do two practical things. Read one of the Gospels for yourself, and Mark is short and a good place to begin. And find a church where the Bible is genuinely opened and taught, so that you are not doing this alone.
If it would help to talk this through with someone, please get in touch. I would count it a privilege.