Where do you fill the hydraulic fluid on john deere 4440?

To check hydraulic fluid in a 2040 JOHN DEERe when setting in the seat with both feet placed on foot boards look on right side behind your heel of foot. Look all the way back to area where axle housing, foot floor board (right foot) and rear housing under seat meet. There will be a small cap that will unscrew and when pulled up will have a dipstick on it.. This cap will look like an old dimmer switch like used to be in trucks or cars. It really doesn't stand out and is about level with the floorboard...