Should be in maps forum.
First of all...
Sounds must be imported in .wav or .mp3 format
They are very common.
Sounds usually do not need careful path changing, but mostly, do not need any paths.
How to import it.
We'd import the sound or music via import manager.
Unless you want the sound or music to replace blizzard's existing sounds, ignore path changing. If so, go to sound editor and find the path for the primary unit's sound to be changed.
Then, go to sound editor. Your custom music or sound should be under imported category on the left. Right click it and use as sound or use as music
It now should be on the sound list.
You may right click on your sound if you want to adjust its properties.
Now, go to trigger editor.
The sound trigger is very easy to find. You can play it when you want during a trigger action.
If your custom sound or music does not work...
Try re-importing them.
Convert them to .wav/.mp3
If it is a sound that does not work, go to sound manager and right click on the custom sound. Set it as user interface.
Good luck!