What fish are you intending to put into the tank?
A ten gallon tank is quite small so you do need to be careful to avoid overstocking, I wouldn't choose anything that grows larger than 5cm/2", and this means NO goldfish. The addition of a heater will greatly expand your options.
Before you can add fish you will need to cycle the filter. The term 'cycle' relates to a biological process known as the nitrogen cycle. This is where harmful ammonia from fish waste and uneaten food is broken down by bacteria in the filter into other organic waste substances known as nitrite, nitrate, phosphate and nitrogen gas. Nitrite is also toxic to fish and even small concentrations of ammonia and nitrite are enough to kill fish.
Traditionally the cycling process was initiated by using fish as a source of ammonia. However these days cycling with fish is somewhat old-fashioned and a far easier and more ethical method is to use an artificial source of ammonia such as fish food or bottled household ammonia (9.5% concentration) to kick-start the cycle. Fishless cycling does require a bit of patience as it can take several weeks to complete however patience is something that is required in fishkeeping, too many beginners fail because they rush.
You will need a liquid test kit to monitor the cycling process. These aren't too expensive and can be purchased from aquatic or pet stores. Only once the ammonia and nitrite read 0ppm will it be safe to add fish.
For more info on fishkeeping take a look at the following links:
http://www.theaquariumwiki.com
http://www.practicalfishkeeping.co.uk
http://www.ocean-wonders.co.uk/messageboard