Fishless cycling with pond water

[Sarah Gabb]

Hi everyone!

I'm super new to all of this but SO excited! I would like to start small for a few months then upgrade my system once I get the hang of it. 

Currently, I have a little 5 gallon fish tank that someone gave me. A friend has a pond that I can use to get started with the cycling process. However, all the info I can find about fishless cycling with pond water just says something to the extent of "it can be done" but doesn't really say how to do it. 

Do I fill up my entire fish tank with pond water or just add a small amount (if so, how much?) How long should I be cycling before I add fish? Are there any dangers of using pond water? 

Also, about how many goldfish should I add to my little tank when it's ready? Maybe 2?

Thanks so much!

Sarah