Idle down, engage the PTO switch, and then speed the engine up.
Do you have the Operator's manual for it? If you don't here is a link to the JD Ag technical info site that has the manuals. https://techpubs.deere.com/
You can download a free
copy of your tractor's Operator Manual. There is a serial number break so you will need your serial number to get the right one.