i created a blog and i cant seem to find were i can upload a new banner anywere , can someone help me

Where did you create your blog ?

i created my blog using one of the layouts provided but would like to add my own header, unfortunately i havent got a clue about css, can anyone explain in simple terms how i can add my own picture header to my blog plz
thankyou
wendy xxx

i have been trying to change my layout using the advanced method and although i am saving as i go, these changes are not taking place, nothings happening, any suggestions welcome
thankyou x

I'm having the same problem. I want to replace the default pic with my own header- but no luck.