convert 9 speed wheel to 10 speed, won't shift to largest ring
You probably need to adjust the 'top stop' screw on the rear mech, and also tighten the rear gear cable.  The rear mech has two small screws.  One of these adjusts how far up/inward the mech will move and the other screw adjusts how far down/outward it will move.  They are used to prevent the chain dropping off the top and bottom of the cassette.  Work out which one needs adjusted (trial and error should be ok) until the mech has the right range of movement to go from the biggest sprocket to the smallest sprocket (but no more).  

Also, you might need to adjust the cable tension, esp if the mech is not moving from the smallest sprocket when you push the shifter.  You can do this normally by simply adjusting the screw mechanism where the cable attaches to the rear mech, and screwing it outward, so as to tighten the cable.  Again trial and error with this should work.  Putting the bike on a work stand where the rear wheel is suspended off the floor, and you can spin the pedals and wheels while shifting the gears makes this job much easier.  Dont be scared to experiment a bit to figure out how things work.