Learning music, where do i start?

[thatoneguy1]

i want to learn the basics of learning music. i know that sounds stupid, so let me explain. i play guitar. I've been playing for a year. the most i can understand are tabs. i want to learn music theory. i ask questions on here (yahoo answers) but they'll answer things and ill read it, and its so complex its in one ear and out the other (even though I'm reading it)so basically this, in the most basic definitions define what these are (i know very little)

time signature (what does 4/4 mean? i tried using a metronome but it doesn't use a slash)
key signature
a measure
quarter/eighth note
a mode
treble cleff

i appreciate it. even if you can list some websites id be grateful. check out my page if you want to see some of the question i asked