The way to bleed is to connect everything. Then there is a 6mm (i think it's 6mm) nut on the front of the oil pump. you loosen it (do not remove) and oil will come out. You do this until there are no bubbles in the oil lines. XPS-2 is pretty runny, just letting the setup sit over night usually clears stuff. There is a spring in the XP oil lines to keep it from kinking, that loves to hold air in it. If you remove the zip ties I just kind of wiggle it all around to get all the air out, then zip tie it back in place.
Or, you can connect everything and just jiggle it until you don't see any bubbles.
You can always add oil to the fuel tank to, if you really want...
Did you replace the oil filter? now would have been a good time since it's all apart... If you don't know the oil they used, I would definitely replace it. Mixing some oils causes them to gel and clog the line... and 2 strokes without oil don't last long. on the XP it's really easy to get to.
Ideally the old oil was tan or red in color. That's XPS-2 oil. which is what the manual says to run in the 951.