To field strip you do the following:
1) remove magazine and clear any round from the chamber
2) Hold the muzzle end of the gun with your weak hand and pull down on the trigger guard with your strong hand with finger curled inside and around the trigger guard -- it takes some force, but it will open if the magazine is removed
3) Trigger guard will pop down
4) Cock the hammer and draw the slide to the rear against the spring pressure, and as it gets to the rear, you can lift the slide off the rails from the rear end and then gently allow it to go forward so the slide can be removed toward the muzzle with the spring inside. Spring may fall out or stay on barrel depending on what angle you are holding the gun.
You are now field-stripped.
Call CZUSA in Kansas City for a free CZ-83 manual.
