On a further note from Charlie P's... you can get stick on lead weights that are circular and fit inside the prop spinner, around the prop nut. That's about as far forward as you can get, hence the least weight added. As a bonus they'll act as a flywheel giving you a smoother idle, but they will slow the throttle response. They also need to be well centred around the prop shaft or they'll be out of balance.
Oh and the cheapest place to get stick on lead weights is a car tyre place... they're the same weights as the hobby shops sell for four times as much, and often the tyre places will just look at you a bit funny and give you a couple of strips for free.
If you check your plane's manual it should tell you where the plane should be balanced... so many inches back from a certain part of the wing. For a maiden start with the furthest forward portion of the manufacturer's recommended balance point.