Easy.
Say you are in C:\main\test\folder1 directory.
The relative path to C:\main\test\folder2 directory would be
..\folder2 with the .. denoting the parent directory.
The relative path to C:\main\test\folder1\subfolder directory
would be \subfolder and it's that easy.
This is of course for Windows directory.
so can i say the relative path can only work if your parent
directories are the same from the source folder, to the destination
folder. (in this case, you wanna go from folder1 to folder2)?