Door
Sliding Door
noun
A door is a door — the kanji and the word are exactly the same.
戸 can refer to any kind of door, but it's more commonly used for sliding doors, since those are the traditional style of doors in Japan. For Western-style or high-tech doors, people tend to just say ドア.
This has the same reading as the kanji you learned, meaning you know the reading!
戸をノックした。
I knocked on the door.
うちのネコは戸をカリカリします。
My cat scratches the door.
この戸は立てつけがわるい。
This door opens and closes hard.