Here's how it's used:
* In the passé composé:
* J'ai ouvert la porte. (I opened the door)
* In the subjunctive mood:
* Il est important que la porte soit ouverte. (It's important that the door be open.)
* As an adjective:
* La fenêtre est ouverte. (The window is open.)
Let me know if you have any other French verb questions!