I'm converting my RAW files to DNG and making edits to the DNG files. I was under the impression that DNG files would store changes like the xmp files for RAW. However when I import files from a CD that had previously been changed or import files to another computer, I get the original files. LR didn't store any of my processing in the DNG files. What'd I miss?

H

If you are working with DNGs and not exporting them back out, then you need to make sure you save your work by going to Metadata>Update DNG Preview and Metadata.
This will ensure your work gets updated into the DNG files.

I found it much easier to work on the RAW files first and then at the end of my workflow, covert all of my images to DNG within LR.