This is a clever way to check how things work, BeamLighting!
Converting your file from QuickBooks Desktop to QuickBooks Online won't hurt your desktop file. It's just like exporting a backup copy online. However, please note that due to the differences between the two platforms, there are some limitations.
Check out the article about exporting your file. It has a video as well.
If you need help, free to go back to this thread. You can also check the video tutorials for QuickBooks Online.