Start by making a list of positive things about yourself. These can be anything that you like about yourself, or things that other people might like. It could be something you like about the way you look, or an attractive personality trait, a success that you have had (even if it was a long time ago), or something kind or good that you did.
Aim for a list of 100 items. You can spend a few days doing it, but be sure to add some every day. Finish it within a week if you can. Then when you have your 100, keep adding one new one every day.
This is a great way to increase your appreciation of your own positive qualities. After a while, looking at this list and adding to it every day, you will naturally come to a point of view where you see that the world is a better place for having you in it.