Because many guys had problems with this, here a short tutorial.
1. Create WDT file with Taliis. File > New > WDT > Set InstanceName.
This is importand. It MUST be your later InstanceName!!! If you rename you must create a new WDT.
2. Now you have a new empty WDT for your map open in Taliis. Save it to your world/maps/YOURISNTANCE folder where the ADTs are located.
3. Now go to the Edit menu ans select Scan Folder. This will load all the ADTs in your world/maps/YOURISNTANCE where you saved your WDT and mark the automatically in your WDT file you have open.
4. Check if there are marks for you ADTs. Here an image of my Meberian.wdt file inside Taliis.
http://is.gd/4JY8wR Click for larger image!
5. Now SAVE you WDT file again to disc at the same location u did last time.
6. Close Taliis. Open Again and load WDT to see if all had worked.
7. Sit down and write an own tutorial for somthing
