This is so confusing, i want to update fallout 3 but the official website only
gives me a option to download update 1.7 , does it mean that all the other
updates are in that update? because it only say something about the zeta dlc

http://fallout.gamesas.com/eng/downloads/updates-v1.7updatenotes-US.html#9

and the website dosn't allow me to download any other updates??

The updates are accumulated and are all included in the 1.7 patch. (And if you have GOTY it is already patched).