Define these instructions

[stanley]

hello to every one !! I am beginner in Assembly language. Could please explain the instructions given below.

1) push  hInstance
    pop   wc.hInstance

2)what is the difference between  this two mov operation given below:

mov  wc.hIconSm,eax

mov   eax,msg.wParam

[NightWare]

push hInstance ; mov the value pointed by hInstance ID, to the stack

pop  wc.hInstance ; mov the top value from the stack at the location pointed by wc.hInstance ID, a structure here, (OFFSET wc + hInstance displacement, corresponding to the element of the structure)

for the others it's similar, but passing by a register instead of the stack.

[stanley]

Thank you :-)