All of this depends on what sort of WAP site you're planning to create.
If you want devices old devices (4 years plus) to access it you might need to code in WML (
http://www.w3schools.com/wap/)
What's more likely is you will need XHTML MP (XHTML Mobile Profile
http://www.developershome.com/wap/xhtmlmp/)
XHTML MP is very much like XHTML, if you can code HTML you code XHTML MP, MP is just stricter.
http://www.developershome.com/wap/xhtmlmp/xhtml_mp_tutorial.asp?page=introductionSimple Hello world in XHTML MP, save the file as helloworld.html or helloworld.htm