OSPF Design

Dear boss
I have cisco 3845 router at DC and cisco 2801 router at 80 branches with dual connectivity. I declared DC LAN and Server LAN as area 0, each branch with separate area. My goal is each branch get DC but not other branch. When i enable ospf all branches get all branch.

How I design ospf that DC will get all branch and each branch only get DC ?
Please suggest me.

Thanking You
shahid