How to add rosters to dynasty?

I downloaded the Roster patch, but I don't know how to use that roster in dynasty.

You can't. If you overwrite the databases in your Dynasty save, you'll lose season data. A few files can be replaced such as teamgear.dbf and coaches.dbf since they don't contain any season data but apart from that you can't apply a roster update to a Dynasty game already in progress.

No, I mean I wanna start a new game in dynasty mode using the rosters that I downloaded.

But when I press new game, the dynasty mode automatically resets its rosters to default.

Turn off 2007 draft.