Learning to play guitar?

Ok, So me and my friends are starting a band and I'm going to be one of the guitarists! I have an acoustic which is severely out of tune (and I think its missing a string) Also I have a kiddie electric guitar which is also severely out of tune and missing a string! I know everyone says use youtube, google it, etc.. My mom is getting me lessons but I want to get a head start on my learning!! Please help =)