I'm a noob so i'm sorry if this question sounds silly.
I hear everybody talking about a green screen(or blue screen) to do special effects.. I don't have a green screen. is this something special or can i buy anything that's green and large enough for a background shot ?
Ideally there are certain shades of blue or green that work best because they are far outside the range of normal color use (so it's rare to wear a shirt that exact blue or green, and skin tones are not close to those colors). But in truth ANY color not being used by your actor *might* be OK as a BG color.
The most crucial part of green-screening is lighting. You're BG color must be lit well enough to stay as close to one shade of green as possible, in order that your keyer (the software removing the green) doesn't get confused.
To really do keying you;ll need a compositing program like After Effects.
If you want to learn more about compositing and Effects, I'd suggest you check out Andrew Kramer's Creative Cow Master Series DVD: Serious FX and compositing - found at http://www.creativecowtraining.net.
The Video training for AE that you recommanded are Advanced techniques for AE.. I don't even know the basics ! would i still be able to comprehend the training from those dvd's or do I need to look for some basic training first?
I've watched the DVD several times, but I am coming from the perspective of someone who already has years of experience. So it's hard for me to say. but from what I hear from other people, even knowing very little, you will still be able to follow and move along nicely.
You may want to post in the AE forum and see what other people think, or you can add a post to this string and see if anyone can tell you what you need to know: