I created three different Terrain Types in data editor (jungle, urban, desrert) and it was no problem adding them under Map Texture Sets
Here´s the problem. The terrain editor tool doesn´t let me add more textures to my map with the terrain editing tool. As soon as I change the current texture set large numbers (only number one) pop up on the terrain.
EDIT: Found it!
There is a texture set button I didn´t notice