To get a garage in Petville you need to level up to it. Once your at level 24 you get your four rooms and buy a Garage for 25000 dollars. Once you see the garage door you need to click on the lower right hand corner that has a door on it and the Petville will let you know how much it is to buy.

Where to find accessories for my Garage?
Currently there does not seem to be any accessories that you can buy for your Garage. Accessories and things for your garage will probable be added in the coming weeks. Once accessories are launched we will update this page

How many rooms can I have in Petville?
Once you get the garage you get another room to clean with gives you two more coins. There are 6 rooms in total that you can get in Petville

How to leveup in Petville?
One of the best ways is to get a lot of Neighbours and or Join Petville pages on Facebook and get a lot of freinds from there.

How to get a Car in Petville?
You can buy a car or get a Garage which comes with a car. The car is just there for aesthetics and looks becasue you cannot drive it around.