My front brake has gotten pretty loose. When I have to brake hard the handle is pulling back so far it's hitting my other two fingers that are on the throttle. I've searched for how to tighten it but haven't found anything.

We will assume that your front pads are fine <that is a prereq>:

Pop the reservior cap off and take a look at the fluid quantity and quality
If low and brown, you need to replace the fluid, flush the lines, refill and bleed.

Kerry's site has a great how-to on this...CLICK HERE

If no problem there, especially with bleeding, do you have the type of brake handle that is adjustable? (it has disc with numbers on the top used to set the grab point)