"Tiene una puerta verde."
Translation:It has a green door.
I'm keeping a list of mnemonics to help me memorize vocabulary. For "door", I think of the episode of Seinfeld where the busboy yells that his cat is missing because the door was left open: ""La puerta esta abierta!" Another memory trick is "puerta" sounds like "port of / point of [entry]"
I hope someone else finds my mnemonics helpful. :)