Most downloads have install instructions, but I guess this one doesn't.

Extract the contents of the folder to a Temporary folder on your desktop.  After this, you should have all the folders pertinent to an aircraft.  IE: model, sound, panel, texture.  If all you have is a texture folder, don't worry.

Transfer the texture folder to the folder of the aircraft it corresponds to.  DO NOT OVERWRITE ANY FILES!!!  This is very important!

Now I need to know if the download contains a file named aircraft.cfg.  Does it?

a300. Your question is not too clear. Do you have a ready-made set of textures or wish to repaint them yourself?

Look in the Readme text file included with the textures. It should have instructions on how to install it as a new selectable option. Open Aircraft.cfg in Notepad & copy/paste the new entry into the appropriate place. If the new Texture folder is named correctly it should show up on the FS2002 menu.

If you have no instructions my basic tute might give you the idea on how it's done. This is a default aircraft & yours will probably have only one [fltsim.x] entry. http://www.simviation.com/lair/Repaint2002.htm
Make sure the entries run in sequence or it won't work. The new texture folder can be named anything you wish providing it follows the standard folder naming conventions. Texture.0, Texture.green etc. The part of the folder name after the period (0 or green) will be the the texture= name in the new CFG entry.