Learn assembly? It's queue of instructions in a text file, nothing complicated.
You don't need a book. Just find a document that has all the instructions listed for your architecture. You can try x86 if you like computers, or maybe some AVR if you like micro controllers.
Generally though, you can't use assembly in much useful way. It is a lot more useful to learn C properly, as modern C compilers tend to create better code than skilled assembly programmer can do in short time.