For Sn00py's terrain, you have to put it as your default terrain.
Download his terrain, and then navigate to your C:/Program Files/Infogrames Interactive/Civilization III/Art/Terrain folder.
Copy all of the files in there to some other place (I have a folder on the desktop) to backup the old ones! Then, drag all of Sn00py's terrain in their and overwrite the old ones. Some files will need to be moved to .../Civilization III/Conquests/Art/Terrain/ (like the Volcanoes and Marsh), so only drag the files to the Civ3 Terrain one that you see there are one of in there (ie; if there are 55 Sn00py files and 50 files in Civ3/./Terrain, only drag the corresponding Sn00py files into the Civ3, and the rest into the Conquest.
To take screenshots, while in the game, press "Print Scrn" (by the F12 and Scroll Lock buttons). Then, open any photo editor (Microsoft Paint will do) and Paste it (Edit -> Paste or Control + V). Then you can save it as a jpeg, and attach it to your post or
upload it for bigger files.
If you have questions, mainly about the terrain part as that's hardest, please ask them!
edit: Cross post with Turner! He has good stuff for screenshots, but read mine for terrain. He didn't have any info on terrain.
