I'm not familiar with the repeater control - but from what I understand it's comparable with a datagrid or datatable but more flexible with its display.
So with that said - most controls do not have any kind of automatic connection and interface to a database. You will need to get the data out of your display and then upload it to a database using a connector.
Read this article:
how to connect to an sql database
this will show you how to connect using a connection string, create an sql command and execute a statement.
I'm assuming you are familiar with sql since you already have a DB set up? (sorry it's hard to tell from a post what someone's skill level is)