New to twitter!

When I was little I had a Batman utility belt, I thought I was unstoppable. Thinking what I'd put in a grown up version & laughing. #IFONLY

How do I put a picture for my profile?

Can I leave tweets on others pages and how???

Are they ways to add cute symbols to my tweets?

Other people gave hearts and smiley faces etc? How do I get those icons? PEASE HELP