Think of the second criminal's words, and how Jesus responded to him. This man was given the privilege of having Christ, himself, assure him of his own salvation. He didn't have to worry about whether he had become a citizen of Heaven. Jesus confirmed it. The man admitted his sin, and turned to Christ; in the most simple fashion. Jesus took note of the man's heart, and knew that he was sincere.
Unlike us, that man didn't have long to live. However, I have no doubt, that had he continued to live, he would have continued to follow Christ -- which is what Jesus wants us to do.
I can't stress, enough, that becoming a Christian is a choice to have a relationship with God and Christ. It's not just a ticket into Heaven, or a choice to start doing good deeds. I feel that it's important to point this out, since, a very common misconception is that "being a Christian", simply means going to church and doing good deeds. Although a Christian should go to church, and is expected to do good deeds, those things don't make a person a Christian, and they won't get you into Heaven.
I've written an entire article about this; which is entitled Relationship Status. I've, also, written an article which talks about the importance of going to church. It's entitled, Why Christians Should Go to Church.
In addition, I've written an article that's entitled Reverence For God. It points out the importance of taking God seriously, and helps to remind us that it's easy for any of us to make a claim about being a Christian. However, it's the decisions that we make, after that choice, which helps to indicate whether or not our decision is sincere.
I strongly believe that, when it comes to learning more about God, the best thing that any human can do, is read a Bible that's in a clear language that that person easily understands.
English is my first langauge, and I choose to read the "Good News Version". I have found it to be the easiest to understand. It's written using the same language that any other modern, English, book uses.
If you don't own a Bible, here's a link that will allow you to buy one from the American Bible Society.
This isn't a referral link, and I don't get a dime, or any sort of kick-back, should you buy one. I recommend this translation because it's very similar to what I use; including line drawings.
My mother gave me one of these, many years ago, when I was six. The book has transformed my life.
If your first language isn't English, then you may find it easier to read a Bible that has been translated into your native language.
The American Bible Society has translated Bibles into many languages. You're likely to find one, in your language, by visiting their website at Bibles.com.