Toe-in is the easiest to explain so I will start there. Toe-in is the amount of difference between the back and the front of the front wheels. If the tires point straight ahead the car would wander and the stearing wheel would not stay in one position. I had a front wheel drive car that the book said needed .5 inch toe-in. I used two blocks of wood the same size, long enough to have about three inches beyond the front and back of the tire. Using the wood to see the out side of the tire, with a tape measure I determined if there was the proper difference between front and back of the tires. By lengthing or shortening the two connecting rods, the adjustment would be brought to the desired measurement.
Caster can be best explained by looking at the caster wheel on any roll around device such as a tank vacum. The caster has the major part of the wheel behind the vertical pivot of the wheel. This keeps the wheel going streight. Camber is the same in referance to the vertical pivot, except instead of looking from the side as with caster you would be looking from the front. The differance you are looking for is the top and bottom of the tire.
I have a mower like yours and I think you only need to do the toe-in adjustment. You can do it by yourself, but it will go faster with one other person. A flat clean place like a drive-way or garage floor would be the best place to test and adjust the setting acording to the manual.
After you make the adjustment, drive mower and feel whether wheel pulls in one direction or the other. Re-adjust as needed.
Good luck and keep smiling!