YOU SAID:

I was looking throug the window and i opened the door.

INTO JAPANESE

私は窓から見ていたと私はドアを開けた。

BACK INTO ENGLISH

I was looking through the window and I opened the door.

INTO JAPANESE

私は窓を通して見ていた、そして私はドアを開けた。

BACK INTO ENGLISH

I was looking through the window and I opened the door.