First generate a patch for others to apply.
For this we use diff
where the first argument shall be the original file or directory where did you started making the modifications and the second should be a version of the file or directory with the modifications already made.:
diff -Naur old_file new_file > your_patch_filename.patch
or (if applied against directories):
diff -Naur old_dir new_dir > your_patch_filename.patch
The options on these diff commands are the following