So, I’m releasing some custom texture packs for StarCraft 2 soon, and I thought I’d write a tutorial on how to use them inside the SC2 editor to accompany the texture sets.
First thing you need to do is to click the import button, the one I circled in red here.

A new window will open up, from the menu click on Data -> Import Files (or click ctrl-I), now browse to the folder containing your textures, and select the textures you want to use. Don’t forget to import a white texture, you will need it later in this tutorial. When you’re done importing, click save (ctrl-s), and you can close the import window.
Next, you need to click on Map -> Map Textures and the Map Properties will open. Click on Modify, a new window will appear again…

With the ‘Terrain Texture Set’ tab selected, right click in the area that I marked above and select ‘add object’, type in a name, click on suggest, and then select copy from BraxisAlpha next to Field Values, hit OK. Another step done!
Now click on the Terrain Textures tab, at the top of the window. Right click in the same area as illustrated above again, and click add object. Give a name for the texture you want to add, hit suggest again, and click ok. Now to the right you should see the same as the picture below, if not, make sure that the red circled button is selected.

click the field next to ‘CTerrainTex_Texture’ and fill in the filename of the texture you want to use, including any subfolders you put the texture in, don’t forget the file extension (eg. grass.dds) and hit enter when you’re done. Now click on the field next to ‘CTerrainTex_Normalmap’ and fill in the name of the white texture. When you’re finished click save.
Back to the Terrain Texture Sets tab, select the set that you made earlier and to the right the same sort of window as above will appear. Double click on the field next to ‘CTerrain_BlendTextures and a window named ‘Object Values’ will appear, there are 2 lists there. On the left are all available textures listed and on the right are the textures available for use in your map. You can only use a maximum of 8 textures in a map. Find your own texture in the list to the left and select it, also select the top texture of the list on the right. Click on ‘Replace’, click OK, and then you can close the Data editor window.
Now, in the map properties window click on the box I circled in red in the picture below.

In the dialog that pops up select your new texture, click OK, and click OK again in the Map Properties window. A dialog will appear asking you if you are sure, click YES. Et voila, your new texture should appear in your map. Congratulations.