Ok, I won't tell you you're wrong 😉 But it has got nothing to do with wap...
What you need, is an smsc connection. There are several ways to do this and it's hugely dependent on which mobile operator you're going to use and to which countries you are planning to send messages.
Usually the messaging costs money, and you need to set up an account with some operator in order to send messages from a web site.
I've developed a straight web -> sms connectivity kit for our company. If you are building something 'real', and not just for kicks, do contact me straight, and I'll tell you how to move forward and give you some pricing info. It's not expensive, but it ain't free either...