add a, b
subtract a, b
compare c, d
jump_if_greater_than to_some_place

some_place:

You pretty much just need an overview on the processor architecture and the various opcodes.
Whilst this gives you a founding in the language, actually programming anything is a different matter.  Then again, you rarely need to program anything significant in assembly these days.

If you come from a higher level language, think of it as a really dumbed down simple, but highly verbose, language.
If you prefer a bottom-up approach, just think of an opcode as selecting a logic circuit from the ALU, and operands as feeding in data (or references to data).

Note: I don't actually do assembly programming, so this is just what I'm guessing.