Need Help with "W3d model texture change" Thread

hi everybody,
first of all i'm new to modelling so go easy on me
i'm making a mod for Generals Zero hour and i ran into a problem which is :

i have a w3d model that i want to change it's texture and i can't find out how to do this !!

in another words ....
for example i have a chinook w3d model ......
i want to change the textures attached to the w3d model file so that i can have the chinook added to another faction but with another texture ..

can anyone help me please ???