Trouble with Features in Assembly

[DaMighty Optiq]

I'm trying to build something strait from a new assembly. When I start a fresh part and create a sketch none of the features are available except for "reference geometry", "curves" and "instant 3D". As far as the extrude boss and cut, fillet, rib, shell etc. they're all greyed out. I don't have this problem when I'm creating a part in "part" mode. I'm only having it in "assembly" mode. I tried watching videos to see if they exit out of anything else and everyone seems to just go to "insert component > new part" then select a plane, start sketch mode, sketch entity, exit sketch mode, boss extrude..... every step works fine up until I need to use a feature.... which aren't available. Does anybody have any clue as to why this is occurring? Thanks in advance.

It's version 2012 by the way.

 

[Unrealze]

Do you right click the part you want to edit in assembly and select "Edit part" (NOT Open part, but EDIT PART)?? You can't use feature in assembly mode, only in part mode. I hope this helps.