I have the same issue - upgraded the wallet but my old DRK won't transfer over.
I don't see any tutorials on the dash website.
There are dead links and non-existent videos that have been abandoned.
Does this help:
"Configurations have been moved from .darkcoin to .dash! You’ll need to do the following when updating your client. First close Darkcoin and backup your data directory.
Windows: %APPDATA%\Darkcoin\
Mac OS: ~/Library/Application Support/Darkcoin/
Unix/Linux: ~/.darkcoin/
After that rename it to Dash for Windows/Mac, or .dash for linux. Next go open the directory and locate the darkcoin.conf file, rename this to dash.conf.
Next, simply update to the newest Dash client and restart."
Pablo.