Your need the NEM nano wallet, download it from nem.io
Register your namespace (use the testnet) from the nano wallet.
You can use this tool to find your namespace pointer address (PA).
Send a massage to the PA to update DNS info. Include the info in a message using a json format.
Bookmark this site and use it to find DNS info and go to NEM namespace websites.
Install the extension for direct access in your address bar. (dot)nem extensions is automatically redirected.