Instructions
Download the Better Heads mod. It's available from a few different sites, including Planet Elder Scrolls at planetelderscrolls.gamespy.com. Enter "better heads" in the Search bar, or click the link in the "Resources" section. At the download page, click "better_heads11.rar," and follow the on-screen instructions. You can also download the mod from morrowind-oblivion.com/mods.php -- click "Morrowind Mods," and scroll down to the "Better Heads" section.
Double-click the downloaded RAR archive to open it, and extract its entire contents to your Morrowind directory -- usually C:\Program Files\Bethesda Softworks\Morrowind. When asked whether to merge directories in the RAR into existing directories with the same names, click "Yes to All."
Start the Morrowind launcher as you normally would, but instead of clicking "Play," click "Data Files" and double-click "Better Heads.esm" to put a check in the corresponding box. If you are running the Tribunal or Bloodmoon expansions in addition to the standard Morrowind game, double-click "Better Heads Tribunal expansion.esm" and/or "Better Heads Bloodmoon expansion.esm" as well. Click "OK."
Click "Play" to start Morrowind with the Better Heads mod installed.