Loading and unloading can be done in subdued light (i.e., avoid direct sunlight, studio flash, etc.).

For most medium format cameras with an automatic counter there are two dots or arrows inside the back or on the film insert that indicate where the film should start. Normally there will be an empty spool on the feed side. Transfer that spool to the takeup side and insert the film on the feed side such that it will unroll with the inside of the paper (and eventually the film) facing the lens. Feed the tab into the takeup spool, and advance the film until the two big arrows on the paper backing of the film line up with those two dots or arrows and then you can close the back and advance the film to frame 1 using the counter.

When you've taken your twelfth exposure, just wind the film all the way to the end until the crank turns freely, remove the film. Fold the flap at the end of the roll and moisten and wrap the paster tab around the roll.