So here are a couple of articles on operating shop equipment, one for the woodworker and one for the metalworker.
The first is on operation of the jointer. The jointer and planer compliment each other in producing straight and accurate 4 sided boards. This is very important in furniture construction and laminated glue-ups. In my opinion, if your finances require you choose between the two, the jointer is preferred by a stretch. You can do all four sides on a jointer (though the two wide sides may not be perfectly parallel). The planer will only do the wide side parallel to the side done on the jointer. You can do both wide sides on the planer, but it will not take wind out of the board without first doing one side on the jointer.
This comparison aside the jointer can do many other operations, as described in the following article from the Winter 1954 PM Shop Notes.
Safety is very important in the operation of a jointer. Check that the guard is working properly and never pass your hands over the cutter head while pushing a board over the cutter head. For shorter boards, make and USE a work hold down like the one illustrated in fig. 7.