An overview of working with the Prusa slicer for 3d printers
To import an STL File choose file -> Import -> STL, Most STL files are metric if it seems huge it may be imperial
Select the model that requires material
If the model has a few places that require support the automatic option can save time. In Print settings select Auto generate supports and specify an overhang threshold.
The green structure around the model is support material
You can specify your desired support areas by using the manual painting option. To paint supports select the icon shown below.
Paint supports around overhangs where it is required. The paint tool has options to identify only specific overhangs as needed.
In this example there are now only supports under the arch where they were painted
Organic support is frequently used because it works well and is one of the easiest to break off