changing colors, images on the default template

i am sorry to post such novice questions here, but i just loaded wordpress onto my site and am filling in posts, etc but i cannot for the life of me figure out how to change the background colors to my own patterns and how to fool with the header, etc. i can’t figure out which page to use to make changes…i seem to have done something because my blog looks funny right now but i am not sure where i made the changes that currently appear (i know where i made the typograpgy changes, etc…)

any help is appreciated – the website is http://www.laughtillyoucry.com/blog