As the title suggests some posters don't know where there smileys are.
So click on the white smiley face, this will give you about 20 smilieys you can use, or scroll down to the bottom and click on "Show all Smilies" which will give you about 300 odd you can use.
Also on your posts you will have to nake sure the "Disable smilies in text"
is not ticked.