func_ entities missing

I have been following the tutorial to create buttons, when it said create a func_button entity I could not find it in the entity list. Apon further study at http://www.hl2world.com/wiki/index.php/Category:Entities I found out that I am missing most of the func_ entities from my entity list (see screenshot), can someone tell me why, do I need to download them seperatly or is anyone else having this problem? I tried searching the forums for missing entity and missing func_button but came up with no results. Could anyone give me some help it would be appreachiated.

www.encore-games.com/images/func.gif (screenshot)

There are two types of entity's, point entity's and solid entity's

Just select your block/solid wich you want to fuction as button and press CTRL+T and scroll down and select FUNC_BUTTON

If you want to see this menu again, just select the brush and press CTRL+ENTER

Thank you very much.