Banner links

Ok, I am completely new to anything word press related and finally launched my website. However, I want to put a banner of another website that I write articles with. I do not know how to do this. Also, can I put up banners from other sites too?

Thank you for all of your help!

Julie

My website is http://www.julieinthesky.com, maybe there is a widget in the word press theme that I do not know about?