If your home warranty covers it, that would be the way to go - get the builder to get it right as it should have been the first time. It's even possible that trying a DIY fix may void part or all of your warranty. That's something you'll definitely want to check into for future reference, too.
If your warranty won't cover it or you want to tackle it on your own anyway, this article lists several causes for noisy floors and some suggested solutions:
Hardwood floors
If you already have hardwood flooring and your floors squeak and pop, you might try the old remedy…baby powder or powdered graphite. Placing these powders down between the planks helps to eliminate the squeak in some cases but is typically not a long term fix. You can also eliminate major squeaks by having a friend stand on the squeaky board while you drive a screw up from below (if you have access) through the subfloor and into the plank. Make sure your screw is of the proper size…you don’t want it to come up through the floor (and potentially into your friends foot). You can determine the depth of your hardwood by removing one of the floor registers.
Floor pops or oil-can noise
If your floors squeak only when you walk across them and sounds like an oil can (a metal flexing sound), you probably have an HVAC duct that is deflecting when the floor moves...
All ductwork in the basement should have a 1” gap between the sheet metal and the joists. This allows the joists to deflect without rubbing on the metal. If you don’t have access to the heat runs because the ceiling below is drywalled, you need to decide how bad you want the noise to go away.
Squeaking floors
This is typically either a nail rubbing or a loose subfloor panel. If you have access from below, locate the squeaky area as someone steps on the floor from above. Check to see if any nails missed the joist in the location of the noise. Sometimes a nail that misses a joist will rub on the framing below as the floor deflects.
If you don’t have access and you know there are no plumbing or electric wires in the location of the squeak, you can try driving trim nails through the carpet into the joists below. Use a trim nail with no head. Be careful not to catch carpet fibers under the nail. This type of repair works about half of the time from my experience. If your flooring is something other than carpet, you are out of luck.
Squeak or tick at a wall
Sometimes a floor will deflect and the wall stays in place...
This can sometimes be repaired by removing the basemolding and driving 3” long screws through the base of the wall into the subfloor (make sure you don’t hit any mechanicals). This secures the subfloor to the bottom of the wall preventing the nail rub and resulting floor squeak or tick when the floor deflects.
