If it came with a manual, you are set. Manuals can be downloaded for free and either printed off, or burned to disk.

 Just remember that it is the same procedure to enter data for each setting change, making it a very easy to set and use controller. To set the rate, push which ever rate number you wish to change "rate * cal", then push the enter button. Change the rate to your chosen rate. Then push enter again, and your set to go. Each data entry will be the same procedure. Find the type of data you want to change, push enter, this opens that data spot to change. Change the data, then push enter again. Pushing enter the second time, enters the new data in place of the old.

 If you loose the calibration settings, usually there is a tag on the components with the info on them, and the manual will tell you how to fine tune from there. Make sure the alarm buzzer is "on" and functioning. This will help you gain confidence in the controller as you learn it. It will alert you when things are outside of perimeters right away.

 If you leave the controller in the cab and unhook the tractor for other uses, make sure the pin connectors between the controller and the sprayer are very clean and in good condition, then keep them that way with dielectric grease and cover them up when not in use. Same with all the connections to the valves. Does'nt matter if they are those weather proof connections or not, check them and make sure they are clean and use dielectric grease on them.

 IMO.