MDWS records the data you upload to it from either the HG612 Modem stats monitoring package or the DSLStats program. These programs monitor the stats from your modem or modem/router, and links to them can be found from the MDWS help page "How do I view my own data?"
If you are not running either of these programs and uploading the stats, MDWS has no data to show.
EDIT: I have experience only with DSLStats, and it took me a little while to
figure out read the manual how to upload the stats.
It's under the Configuration>MyDSLWebstats tabs!