Select the area of the screenshot you want, then go to Edit -> Copy. Then open up a new canvas in paint. Select Edit -> Paste. Save it. Then, go into the TK's tile editor and select Import -> Grab Tiles
Open up the image in the popup window, then do a batch import at 32 * 32. Then go into the tileset editor and add all of the resulting tiles to the tileset. Then save the Tileset and delete the original tiles (the ones with the *.gph extension)
