Sending SMS from VB using an SMS service provider

Hi there.

I work as IT admin in a company, However I am being assigned some
programming tasks as I know a little about that.

I have discussions with a local company who provides sms sending
service from following interfaces

FTP - (write values in a predefined file format & upload it)
HTTP - (write parameters in a url & go for it)
XML - (a predefined file format, fill it & post it over HTTP)
Web Interface - (go to service provider web, log in & send messages
from there)

(I have got these file formates & other detailed info about these
interfaces)


As Our company's software has been developed in VB 6, I need such an
application that works from VB program, an end user will provide values
like

- Mobile No.
- Message Text

& hit send button, the VB application should send this message to that
specified number. It will also use the Login Name, password & some
other message setting but end user will not know this (that can we do
inside our code or we'll keep these values hidden from end user by any
mean)

Can any one guide me, How I can accopmlish this task.

I will be greatly thankful

.