You should get a service manual,makes life easier and will save you a lot of grief.
Ditto but if you insist on not getting the book right now the crank case oil plug is on the front left corner of the transmission pan (3.5 qt's) the tranny plug is center further back(I dont rember how much right now)and the primary plug is under the derby.( 1qt)
With the service manual, I highly suggest the "Fix My Hog" dvd. It will go through the service step by step in good quality detail.
Those two items will be some of the best money you will ever spend for your motorcycle. Good luck on the service.
Remember:The twin cam 88 need a derby cover gasket, timing chain cover gasket (adjust timing chain in 1 in incraments), oil plug o-ring, tranny plug o-ring, primary o-ring.
We just had a thread asking the same question about a week ago. Do a search, there where pictures of the plugs included in one of the responses. And ditto the manuals. Might wanna search for how to repair a stripped out plug too.