Would love to see pictures as you progress!
First, learn what you can about the nitrogen cycle in a pond. Start here:
https://www.thepondguy.com/pro...
Here is a link for water parameters:
http://www.watergarden.org/Fis...
Plenty of resources that will help you on the same site:
http://www.watergarden.org/Pon...
I would also recommend a few water test kits:
Measures pH balance, Ammonia content, Nitrite levels and Phosphate content
Measures GH & KH
Detects high nitrate levels from 0-160 ppm