Check the oil level. First, locate the oil dip-stick (marked in the first image by red).

Pull out the oil dip-stick and wipe clean it clean with a paper towel or rag.

Re-insert the oil dip-stick completely and pull it slowly out.

The oil should reach to the safe-fill area on the stick (marked in the image in yellow). If it doesn't, add more fresh oil through the funnel until it reaches this mark.