How can I solve the connection error in SQL ?

Question

I have created a database in SQL but when I want to access it by C# but the compiler can't access and open database.

 

the error is :

 

An unhandled exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll

Additional information: Cannot open database "Restaurant" requested by the login. The login failed.

Login failed for user 'Milad0007\Milad.H'

 

 

Please guide me to solve it.