I downloaded Bitcoin-qt. It's working. I received bitcoin into it.  I want to know how to back it up. I have checked all the folders and files under C:Program Files (x86) > Bitcoin.   There are not .dat files in there. There are files that start with "wallet" but no wallet.dat file.  Where is it?  They are all CPP and H files.

I downloaded Bitcoin-qt but cannot complete the initial sync because i dont have enough space on my laptop. I want to save my bitcoins on a USB drive. Do i have to complete the sync to do this?