totally a newbie in sending phone number to a webserver

I registered a SMS web service and I have username and password
and there are methods as follow which I can use:

balance
receive
send
send to all
send advanced
status
status advanced

suppose I have a form and I will get the phone number from user
also I have user name,pass and url of the web service
like $phone['number'],$user,$pass,$url

I don't know what exactly I should do to force the php code read from the
functions of the web service does including the url enough?
I am totally mixed up.

can someone tell me what is happening in this procedure?

is there any tutorial so that I can understand it?
I tried to use sample codes but they were different from which I wanted.

Thanks in Advance.