warm the oil up.....take a little ride.
find the oil drain at the bottom rear of the oil tank. drain oil. replace filter.
the HD style V-twin is a dry sump engine. there shouldn't be much oil in the crankcase. DO NOT remove the plug in the bottom of the crankcase!!!!! if you strip it, you will have to replace the crankcases......if it falls out, you will loose all your oil while riding.
fill the oil tank with the oil of your choice. any 20w-50 if acceptable. do not top it off! the oiling system requires an air gap at the top of the oil tank. typically 3 quarts of oil.
if you can find the oil feed to the oil pump, you can pull that line and drain the oil tank from there...but if you do.......put a couple of quarts of oil in the tank and pull it back off to make sure it is full of fresh oil before clamping it back onto the oil pump or you will burn up the oil pump and the engine.
there should be 3 hoses going to the engine from the oil tank. one line to the oil pump (feed), one line returning from the filter (return) and a line coming off the crankcase, just above the oil pump (vent).
let me know if you need more help.
it should take 3 BUT...remember what I said about the air gap at the top of the oil tank!
if you over fill it, you are going to have a mess to clean up.