It can be confusing - listening to all different advice, dealing with all new equipment etc. But once you understand the principals it becomes a lot clearer. Basically, for a Leopard gecko, you need heat on the floor of the viv. This is usually provided by a heatmat which covers about a third to half the floor area. This allows for a cooler side as well so that they can thermoregulate - that is - position themselves at the temperature they need to control their metabolism.
So - heatmats - place it on the floor of the viv. If you have a wooden viv it goes inside the viv, with glass vivs (not the best choice for Leos IMO for many reasons) then underneath the viv. The mat MUST be attached to a thermostat. Just the cheap mini-stats are fine. You do not want a dimmer stat - these are for bulbs. The thermostat probe is placed over the heatmat. You then also need a thermometer - digital are far and away the best. Place the probe to this also above the heatmat - usually next to the stat probe. Then what you do is adjust the thermostat until your thermometer tells you that you have the right temperature on the floor. I aim for 92-94F - this is higher than some older books / caresheets will state, but after many years of keeping many Leos I find this is best. Don't worry too much about the air temperature - normal room temperature is fine. You should not normally need a heat lamp. I hope this helps. Once you have all your kit (heatmat, sat and thermometer) it becomes a bit more straightforward.
If you go to the lizard section there are very good guides to setting up a Leo viv. http://www.reptileforums.co.uk/forum...ard-gecko.html