I recently was playing my guitar (Schecter: Diamond series Damien 6, with floyd rose) and as i was tuning it, the G string would not tune. The Floyd wouldn't let it go low enough for the tune it needed. I don't know what this mean or what to do because this is my first FR and this is the first time its done this. If someone could please help me out or telling whats going on i'd be really appreciative.
Hey mate, since you're not familiar with how a floyd works, I'll go over it briefly as this is quite a basic question (unless I've completely misinterpreted your question) once you know how the system works. If you already know this I apologise.

You have the fine tuners at the bridge, and your regular machine head at the head. At the nut you'll find bolts which lock a bar down onto the nut (where the strings touch where the head connects to the neck). That's where your strings are 'locked', allowing you to use the fine tuners. The idea behind this is that you have a floating system, where the strings are locked so they can't detune when doing bends, dive bombs etc. The fine tuners allow you to make slight adjustments according to the wear of the strings due to stretching etc.

When you want to completely retune your guitar, or change strings, you first need to undo the locking nuts. This lets you use the machine heads. It follows that to allow for maximum adjustment at the fine tuners (the bridge), you want them to be set up so that once you lock it again you can both tighten and loosen as required. To do this what you want to do is undo/tighten the fine tuners until they are approximately at half height.

So to answer your question:
1. undo the locking bolts at the nut (where the strings touch where the head joins the neck). You should have been given the correct sized allen key with the guitar.
2. set all fine tuners to approx half their height (i.e. screw/unscrew until they are half way adjusted).
3. tune the guitar using the machine heads as you would tune a regular guitar. The strings won't snap because they aren't locked.
4. Do up the locking nuts again (don't over tighten them!)
5. tune again with the fine tuners- should require very little adjustment.

Hope that helps.