How can I know about compute capability and sm of my Graphics card?

You should just use your compute capability from the page you linked to. For example, if your compute capability is 6.1 us sm_61 and compute_61.

SM stands for "streaming multiprocessor". The arguments are set in this confusing looking way because they are used as arguments for nvcc where the compute_XX sets the architecture for a virtual (intermediate) code representation and sm_XX sets the architecture for the real representation. Unless you have a good reason, you should set both of these to the same thing.