You can provide a hard coded path like "c:\main.swf" to tell SWF Studio exactly where to find your SWF file. The problem with this is if you move your project file the main.swf has to stay in the same location for everything to work properly. With large projects it becomes difficult to keep track of all your files.
SWF Studio has a solution in the form of relative paths. Anywhere you can supply a path to a file in SWF Studio you can use a relative path. A relative path is one that begins with "." or ".." and all relative path references are assumed to be relative to the location of the SPF file they are in.
"." means starting in the current directory and ".." means starting in the parent directory.
So if we had used ".\main.swf" in our original example, SWF Studio would look in the folder where the project file is for a file called "main.swf".
If we had used "..\main.swf", SWF Studio would look in the parent folder of where the project file is for a file called "main.swf".
If you use nothing but relative paths in your project and you move the folder that contains your project (along with the other files it depends on) then your project will continue to work without any changes.