PaulS:
is it possible to host the webpage on my computer and send the commands to the ethernet shield to tell the uno to open/close the garagedoor?
The Arduino-as-server can be sent GET requests (or POST requests, but GET is easier to deal with) that contain the data needed for the Arduino to determine whether to open or close the door, as a result of a submit button on a form served by a different server. That server could be your PC.
Also can someone give me some information how to do this?
How to do what? Have the Arduino act as a server? Have the Arduino parse the GET request? Have the Arduino open and close the door?
What part are you going to be doing?
Thanks for the information 
I'll probably be hosting the page on my computer so I can also put videofeed on it from a webcam