Move local SQL Server DB to hosted SQL Server
First, you need to find out from the hosted provider the username/password of a user with either the sysadmin fixed role, or at minimum CREATE DATABASE rights (intermediate: dbcreator fixed role).  This will let you run the restore, if SQL can access the .bak files.

Second, you need to change ALL the passwords for ALL the users on your hosted SQL Server.  Long (25+ character) random passwords stored in KeePass or similar are ideal.

Next, you need to remove all domain users from the restored database; they're worthless now.  You need to change your apps - whatever uses the database - to use the new SQL user and password rather than whatever was previously used.

Next, configure backups on the hosted site.

Next, RESTORE a backup from the hosted site - make sure it works!!!

Optionally, configure the hosted instance to force SSL connections; talk to your hosting provider about certificate generation and installation, then use sys.dm_exec_connections.encrypt to validate (it does take a service restart).

Optionally, figure out how to pull backups from the hosted site local, in case the hosted site has serious issues (possibly legal issues, for instance) and you lose everything there.