i have fallout games on my libary but when i press on fall out that is back it does not say i own it why?????

It's considered a different thing. The one in your library were back from when Interplay still owned the games, which is identified as "Classic". The new ones have Bethesda branding. I still don't know if the games themselves got changed at all.

soo what too do then?

Well, if you want to play Fallout, go to your library and download Fallout from your library.

You don't have to go through the store interface. Just go to 'Account' at the top, find the game in your library, click the arrow on the bottom-right of the game's box (by the name), and select 'Downloads'. You can download the installer and the extras from there.

If you wanted, I'm sure you could also buy Fallout from the store again, but you wouldn't gain anything.