Tiled Can't Find My Tileset

This is my first time using tiled, and so far, it’s a pretty good editor. But, my problem is, that Tiled can’t find my tile set. So now my map layout looks like this:

How can I fix this? Every time I open a new project and then come back to it, it does this.

Please help. :disappointed_relieved:

Nevermind got it to work.

What was the problem?