how do i reformat my harddrive my computer info is listed below?

i hav microsoft windows xp professional version 2002 service pack2
COMPUTER:
Intel(R) Pentium(R) 4 CPU 3.00GHz , 448MB of RAM
i want to reformat my ASUS mother board
how do i do this
dont tell me this is a bad idea dont ask whats the reason …dont be rude…dont [...]