Well if you add fish now they will almost surly die at first, It take 30 days or so for the good bacteria to grow in your system. How ever if you add some ammonia to the water (a odd prawn, fish food, or pure ammonia) this will help the bacteria to grow.
As for testing your water, it's far to soon to get true results and you should be testing for ammonia, nitrite and nitrates.
Once you have 0 ammonia and 0 nitrites your system will be safe to add a few fish, stock slowly, 2-4 small fish or 1-2 medium fish and then add same again after 10 days this then should allow the system to build up slowly and safely, resulting it very few deaths.
If you just go out now and buy some fish then your be looking as lest than 50/50 changes of survival and a lot of problems resulting from stress.