my macpro says i've downloaded Elcapi tan- yet it looks like I only have OXS 10.9.5 and also says my iphoto update is incompatible???

I bought my Pro in early 2013, ive not downloaded an update to my knowledge. Iim finally taking the time to update my Pro and clicked onthe apple icon and "about this mac" it says im currently on O SX 10.9.5

the options for updating it were, mavericks and Yosemitee. Both had the "download" button next to them so I went ahead and started them both not knowing if I should have only chosen the latest which looked to be Yosemitee.???

Then, as im digging further and waiting for the VERY long downloads, i notice on another page, it says i downloaded El Capi tan already?? yet there were three incompatible apps.. One being iphoto! My iphoto is a bloody mess. infact thats my least favorite app i have to say, its confusing, it crashes, spinning rainbow wheels, needless to say i can not even use it for work which is most frustrating. But now I m told its incompattible?to what? which down load??

im confused...