You'll have to manually open a command-line box and navigate to where you unzipped the TGA2STL exe file. Put your TGA images in the same folder to make it easier to use. You can also create a batch file that you can drag-and-drop TGA files onto that will automatically do the command-line work for you. In fact, I'm surprised I didn't include them in the Zip file. If you visit the TGA2STL github https://github.com/DEF7/TGA2STL there are 3 batch files named 'high', 'med', and 'low' .bat. You can save those to your TGA2STL folder and then you will just have to drag and drop your TGA image onto whichever one you want, depending on the number of polygons you want the mesh to have (i.e. quality level). You can also drag/drop TGA images right onto TGA2STL itself but you won't be able to control the quality level of the STL mesh it generates.