How do I open a lemark 33 ink cartridge to refill it? -

I want to refill my ink cartridge, but I cant get it open. Its for a x5450 lexmark printer

Incorrect cartridge error message could mean a clogged printhead. Are you certain you did not accidentally touch the gold areas (printer points) as this can put oils and dirt or residue on the cartridge. Gently wipe both heads on cartridge very softly with a non perfumed baby wipe! Now try printing again.

Peel off the label on top of the cartridge n under it there are the filling holes. the top hole thats by it self its for magenta color ink the hole in the left is for yellow ink and the one in the right is for cyan ink