At first, you need the Levelshot Template, download it here. Edit it with Gimp or Photoshop.
The Screenshot for the Levelshot
Look at the best place on your map or the place you want, and make the screenshot with F11(which you add into the template), finally you find it under "q3ut4/screenshots". It is recommended to make the screenshot with these references:
cg_draw2D 0 -This will remove the GUI cg_drawHands 0 -This hides the gun fov 90 -Yes 90, distortion isn't a pretty thing. r_gamma 1 -Anything other than 1 will make your screenshot look horrible. r_picmip 0 -Highest quality textures. r_simpleshaders 0 -If your using the latest renderer, this enables all the new effects. r_bloom X -Season with bloom to taste; I find r_bloom 4 a nice setting. r_fancywater 1 -If applicable, enable fancy water.
Saving the Screenshot
Save the levelshot under "q3ut4/levelshots/YOURMAPNAME.tga" (or as a .jpg to save space) and pack it with the right folderpath (levelshots should be the name of the folder) into the .pk3-file from your map.
- The usual resolution is 1024x1024
- If Possible, enable antialiasing for a sharper screenshot.