1. Click "Save As" or "Load" button, then "Open Folder"
2. Find your level file (*.txt) and icon if it was created (*.png)
3. Share them via mail, dropbox etc. I suggest to compress them first.
4. Open folder with levels (point 1) and copy downloaded files there
5. Open _savedLevelFileNames.txt file with any text editor and add a new line with level file name
This process will be simplified in the future.