Hi Jackie, I'm sorry you lost your fish and found yourself in this position.
Water changes will be you and your fish's best friend for a while. Hang in there and be patient. It going to take some work on your part.
Here's a basic explanation of the
nitrogen cycle:
First your ammonia (from fish waste and left over food) will rise.
In a few weeks bacteria will start to develop and you'll see the
nitrite levels rise and the ammonia levels start to drop.
After a few more weeks a different kind of bacteria begins to develop and you'll see the
nitrate levels rise and the nitrite levels drop.
Ammonia and nitrites are toxic to your fish.
So until your cycle is complete, you need to keep the levels down with 50% daily water changes.
Using Prime as your water conditioner will detox the ammonia for 24 hrs between water changes.
When you having readings of 0 on both ammonia and nitrites with some nitrates showing, your cycle is done.
Or you can try and find some Tetra SafeStart. It's a bacterial additive that many members have used to quickly cycle their tanks.
Don't be fooled by products with similar names.
If a store doesn't carry it, don't let a salesperson talk you into buying any other bacterial additives. It probably work and will likely set your cycle back.
With Tetra SafeStart, you add it once. The others you have to keep adding it with every water change because the bacteria they contain are not aquatic and die off quickly.
Good luck, oh and don't feel bad many members have started out the same way you have.

John!