How do you add payment modules?

[hedera]

I hate to ask dumb questions, but: my business associates want to set up their merchant account with WaMu, which uses the TransFirst payment g/w. They need a business account with a bank because they regularly deposit cash, and they want to do it all in one place. I have a ZenCart installation which ONLY has Authorize.net and LinkPoint, and I see no clear way to add another module. I understand that TransFirst has a ZenCart payment module - but even if I get it, how do I install it? The front end supplied by our ISP is worse than useless; I've been using Microsoft Expression Web to build the site.

I THINK that I install a new payment module just by uploading all the files to:

ZenCart/includes/modules/payment

Can someone confirm whether this is true?? If I do that and then log into ZenCart, will the admin interface pick it up and let me configure it??

Help...

[serge111]

it's true, u just upload the files...