Plzzzz solve it.

Explain the purpose and working of each instruction written in the following lines

mytask:      push bp

              mov  bp, sp

              sub  sp, 2              ; thread local variable

              push ax

              push bx

              xor  ax, ax             ; use line number 0

              mov  bx, 70             ; use column number 70

              mov  word [bp-2], 0     ; initialize local variable

mytask2:      push ax

              push bx

              push es

              mov ax, 0xb800

              mov es, ax             ; point es to video base

              xor bx, bx             ; initialize to use first shape

mytask3:      push bp

              mov  bp, sp

              sub  sp, 2              ; thread local variable

              push ax

              push bx

              push cx