For now you might get one more sword tail then let the tank cycle through the ammonia, nitrite cycle.
Putting anymore fish in would be very stressfull to the fish as the cycle stage builds up in the tank.
ammonia and nitrite are toxic to fish and at high lvls can kill them.
It will take 4-8 weeks to have your tank cycle. during that time do light feeding and monitor the levels of these toxins by testing the water or getting it tested at your Fish Store.
After your tank has cycled add a few fish every couple of weeks.
A Properly cycled and maintained ten gallon tank can hold about 20-25 inches of tropical fish.
Look closely at the fish you do like and research them for water conditions, tempature, and which fish are compatible with them. during your cycle time is the best time to plan this out