How big? I want it to have things like frogs lizards and fish. You know plants around it and stuff.
Uh not that big maybe like 300 gallons or something like that.

At least 5 acres, In my opinion

Depends on how big the pond will be.

There Is No Size It All Depends On How Big You Want Your Pond I Would Go Will 1 Acre

You really have to go to your town hall and find out what the laws are in your town. Ponds can change a lot in the environment and sometimes the town will fine you if you put in a pond. A thing you can do is get one of those plastic little ponds that they have at places like Home Depot and some plant stores.

not that big. i have a really small back yard and have a decent pool. you can shape the pond to work with your space in your yard. it doesn't have to be round.

I have a small backyard and a pond (which I might add I love). I started out with a pre-fab pond from Wal-Mart. Then went to a larger liner pond. When I had a question I went to www.gardenweb.com..then go to forums and then to ponds and aquatic plants. They have been most helpful for me.
Check them out and I am sure they will help you with all your questions.
Hope this helps..