Oh you are serious ...  

The antminer U2 can be used to mine SHA-256 based coins.
Litecoin is a scrypt based algorithm, so you cannot mine litecoin with antminer U2.

Here is a good place to start:
http://www.coinwarz.com/cryptocurrency  

However the calculations does not take difficulty into consideration...

I can see that you knowledge-wise are almost starting from scratch, you could consider getting a used graphic card, I have seen a R9 280X sold for less than $100. And then mine a bit and get some experience. You will not make a profit, but you can make some experience, and after you will still have a ok graphic card to play games with.

Alternative strategy would be to invest in a PoS coin, like MINT or BC. Then use your normal PC to stake coins. But getting into altcoin is also a risky business.

But really, you should HOLD ON TO THOSE BITCOINS and not spend them.