If you are on a budget, I would suggest, instead of tiles, which can be expensive, since they are mainly geared toward commercial uses- finding remnants.
Most tiles are glued down, and as the prior person suggested would be easier for the first time when using a solid color.
You will need to see what kind of glue the manufacturer suggests, or you might void any warranty issue that could arise in the future. The glue for carpet tiles will be an acrylic copolymer that needs to be either trowled or brushed onto the floor. Allow adhesive to dry completely and turn translucent before proceeding with the tile installation. If it is still wet, it will become permanent (verses the "removable") bond with the tiles.
This kind of glue is used with tiles so that the squares can be easily replaced when damaged ...a feature that is important with commercial carpet!
We use AD-VANCED AIRTECH #320 for installation here at our flooring store.
Hope that helps! Good Luck......you can also find good deals at LOTSOFCARPET.COM You will be able to view and purchase tiles over the internet!