The things college didn't teach me....

So I graduated last Saturday and have started my new "career" and have some questions about things college didn't teach me.

WTF am I suppose to do with a 401K ?!..... So freaking lost. I've had my dad/future father-in-law try to help but they just made it worse.
Is there any simple way to go about how to split up my money that goes there?

I'm currently (have since Feb when I got the position/started getting salary) putting away 10% - company matches 5%... of that 10% its broken up to a few different places - thats all the more specific I can be.... the only thing I've been told is "be risky - you're young".

My if anyone has simple answer to the following:
How much should I put away ? -- any rule of thumb?
Where to do put it?
Does it make more sense to put the 5% match in and then take the other 5% and dump it into an IRA I started a few years ago or just keep all 10% going through my work's plan?