If you are starting over your new system wont be cycled. If you dont know about the nitrogen cycle this is a good explanatory video of what its about.
You will need to cycle the tank. I will assume your budget doesnt run to testing kits etc at the moment, so it would be a good idea to regularly change the water. Maybe 25% water change every other day for a month, then slowly cut back on the frequency until you are changing 25-30% per week. You dont have many fish at the moment so it shouldn't be difficult to keep the water quality good until you are cycled.
Link to some useful stickies for new fish keepers. I think there is a post on what to do if you suddenly find yourself with fish.