Completely newb-question about gearing

So i've got the puny 2.1 diesel. Good enough for a DD but the craving for slightly bigger tires is coming.
I'm just going 31" or 32" depending on what offers i can find, but i still think the 87hp engine will struggle.

I've never had to regear before (my old Chevy had plenty of power), would someone please give me a quick rundown on what's involved and a ballpark cost-estimate?

Thanks

modified tech - http://www.naxja.org/forum/showthread.php?t=46901&highlight=gearing

Sorry bout that. Apparently i simply can not search.. My bad.

Thanks tho