There should have been a "read me" file that tells you what to do with each file but if there was none or you just missed it try looking at this. Check out this tutorial and make sure you followed these steps exactly Shadow:
http://feral-heart.com/index.php?option=com_jfusion&Itemid=2&jfile=index.php&topic=21635.0%20newwindowAlso sometimes you don't just press replace when it comes to installing a download marking.cfg file because the cfg file the person gave you might just be coding for their specific markings and not include the original game's default marking codes so if you just hit replace you will over write the coding for the default files. The correct thing to do is copy the new downloaded marking.cfg codes and paste them to the marking.cfg file in the main Feral Heart folder individually if the downloaded folder only contains the marking codes for their markings.
When you open the marking.cfg file in the main folder it should look like this inside:
[Fbody]
Cheetah;fmarkCheetahBody.png
Cheetah 2;fmarkCheetah2Body.png
Cub Spots;fmarkCubSpotsBody.png
Back Splotch;fmarkBackSplotchBody.png
Jaguar;fmarkJaguarBody.png
Jaguar2;fmarkJaguar2Body.png
King Cheetah;fmarkKingCheetahBody.png
King Cheetah 2;fmarkKingcheetah2Body.png
Leopard;fmarkLeopardBody.png
Leopard2;fmarkLeopard2Body.png
Leopon;fmarkLeoponBody.png
Liger;fmarkLigerBody.png
Marble;fmarkMarbleBody.png
Marble2;fmarkMarble2Body.png
Ocelot;fmarkOcelotBody.png
Scar;fmarkScarBody.png
Snow Leopard;fmarkSnowLeopardBody.png
Swirl;fmarkSwirlBody.png
Tiger;fmarkTigerBody.png
Tiger 2;fmarkTiger2Body.png
Siamese;fmarkSiameseBody.png
Bubbles;fmarkBubblesBody.png
Spiral;fmarkSpiralBody.png
Underfur;fmarkUnderfurBody.png
Stripes;fmarkStripesBody.png
And so on....
You would paste the downloaded marking codes into the catagories they belong in under those lists
-[FBody]
-[FHead]
-[FTail]
-[CHead]
-[CTail]
-[CBody]
Then you restart the game.
Hope that helps.