Heaven is where God is. And where God is there is no evil. There is no pain. Everything and everyone in heaven is good. Consider what that means. Love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, and self-control. (Galatians 5:22-23) Everyone always responds in love. And love does not mean warm, fuzzy feelings. Biblical love, agape love, is sacrifically meeting the needs of others. Imagine a world in which everyone does that. That's heaven. A place of never ending peace.
God is the source of all that is good, and nothing evil (sinful) can exist in the presense of God. That's what it is like to be in heaven.
Those who truly trust in Jesus (God) as their Savior from the just wrath of God (punishment) for sin -- punishment for everything thery've done wrong and every time they have disobeyed God. The famous verse John 3:16 says, “For God so loved the world, that He gave His only begotten Son, that whoever believes in Him shall not perish, but have eternal life." BUT, and this is important, you must believe in someone who can actually deliver on that promise. You see, many people believe in a Jesus (the Son) who cannot save them. Why? Because it is a Jesus of their imagination, not the actual Jesus of the Bible.
Are you trusting Jesus Christ, and Him alone?
For by grace you have been saved through faith; and that not of yourselves, it is the gift of God; not as a result of works, so that no one may boast. - Ephesians 2:8-9