Yep ammonia is the first step.
Ammonia to Nitrites to Nitrates. You’ll want to wait until you have no ammonia and no nitrites. When nitrates are minimal, you can add plants and fish which help. The goal is to eventually get some beneficial bacteria going. Algae is a good sign (at first). Add fish slowly. There are other additives to get your tank and bacteria going, there’s a lot out there to choose from.
Beware of spikes of ammonia with the addition of fish and the best way to combat this is to stay on top of your water changes. Especially for a 10G.
Keep doing weekly water changes, don’t clean out the filter, and water test often. Should be good to go with plants around 3 weeks and I’d wait another 2-3 weeks after that to add fish.
If you’re using additives you should be good to go for fish in 3-4 weeks I’d imagine.