How to write a tool for changing video mode under DOS?

Hi All,I never developed program by using Assmbly, but now I need a tool for changing video mode under dos. I know how to change video mode under dos by using debug.exe tool, it's very very simple.
For example, change video mode to 800x600/8bpp:
mov ax,32 ;AH=00h, change video mode; AL=32, 800x600/8bpp
int 10
int 3
But how to write a program by using Assmbly?
Thanks for your help!