I don't think you're being dumb. I don't quite get what you're asking, though.
Valet parking is $10 a day, which is much lower than average for hotels.
You can use it for a few days or your entire stay. Just be sure to let them know you're done using it...once in a while, they just keep charging because they don't know. Check your bill at the end of your stay to be sure you weren't charged for days your car wasn't in the valet lot.
When you are done using the valet service, just move the car to self-parking. Even if they don't have to retrieve the car, if it is sitting in the valet lot, you get charged.
You can't get your own car out of valet - they get it for you. Kind of the point.

If you call from your room, the car will usually be there when you get to the lobby or they'll be pulling up soon.
HTH!