Hi,
If the db is on the same machine you can put localhost for the server name. The part you have with \MOJO is the name of the db instance. Did you really name it MOJO when you installed SQL Express?
Typically the instance name will be SQLExpress so you could put localhost\SQLExpress, or if you made it a default instance then no instance name needs to be specificed you can use just localhost
Hope it helps,
Joe