to download files off a folder on my website and put them in a specific folder in my sd card....is it possible?

Would you really need this, though? You can just use a PC.

It would be good for Categorii.

Yes, there are already existing network functions in devkitPRO which can download files from any server and place them in any location from the Wii's RAM to peripheral devices' ROM.

but i wont be the only one download these files

and thanks for reccomending categorii