depression

this is my first time posting on this forum or anyforum for that matter. i wanted to get others input on my problem. you see, everyone of my friends are like your all depressed all the time, okay, i know i have been and i'm trying to get out of it, but i guess i;m not doing such a good job. so how do i get out of depression, i don't even know why i am depressed in the first place, i'm sure that would help if i knew that, oh well if you ahve any advice for me i would like to hear it, thanks everyone