Replacing ink cartridges in the HP DeskJet 3630 is a straightforward process. Open the ink cartridge access door, typically located on the front or top of the printer. Wait for the carriage to move to the center. Gently press down on the expended cartridge, releasing it from its slot. Remove the new cartridge from its packaging and pull the plastic tab to remove the protective tape. Slide the new cartridge into the corresponding slot, ensuring it clicks securely in place.