Would help to know where you will be staying.
Start here:
http://www.golynx.com/maps-schedules/routes-schedules.stml
You will need route 56 south from the TTC.
Then you must get off somewhere on US 192 (careful, it goes into Celebration Place for a short distance).
Change to bus route 55 Westbound, and make sure the driver knows you want to get off as close to Rolling Oaks Target (just before FL 429 Western Way) as possible.
Coming back you need an eastbound 55 and change to a WDW bound 56.
Be aware the walk to Target from the bus stop is about a quarter mile and you have to cross at the light ... Google maps suggests the bus stop is about 100' away from the traffic light.