People say I have a hard time showing affection, but I really don't know how to. I try not to be so rude but I can't help it. What should I do?

Expressing Affection. If you did not grow up in a home seeing your parents expressing warm/positive feelings toward each other, you, and/or siblings, being affectionate is probably foreign or unnecessary to you. Start slowly by greeting your close friends with a hug; holding hands with your boyfriend. The more you initiate physical contact the awkwardness will fade. The new behavior will soon feel natural. Enjoy!
Good idea! Your heart's inthe right place. You need to learn lots more about people. I would suggest psychotherapy with that in mind, as well as group therapy with people your own age - that will help bring problems to the surface. You really can learn this. It may also be a great help to find out why it''s this way. Work hard ; good luck!
Affection. You probably were not born with inhibition to express affection. Try to confide in a close friend and uncover the causes of your discomfort. Consult a mental health professional who can help you learn how to let go and express yourself without anxiety. Bst.