On my Boomer 24 there is a lever on the left hand side. It has 4wd, N and 2wd.
PTO is controlled by the engine speed. 2400 rpm = 540 PTO for my boomer 24. Your speed may be different, but that is printed on the dash right above or under the tachometer for me so hard to miss.
I love my boomer 24 it runs like a champ. Easy to use for a first time tractor owner.