A portion of your dipstick at the bottom has a flat face. The oil level should be somewhere on the flat portion. An owner's manual work help you out a lot. Go here, type "225e" into the engine type box, and download the manual it brings up.
As long as the oil level (without the dipstick screwed into the drive) is within the flat/cross hatched area of the dipstick the level is fine.
Personally, I try to keep it within 1/2" of the top of that hatched area but not over full.
