connecting to the SQLServer database with C#

i find out a connection string to create wizardless connection to the SQLServer database, but i don`t know something about it, the question is where can i find SQL version for example SQLEXPRESS and where is application.StartupPath in Visual studio folders, so i can copy my database to that path, any better method will be appreciated, below the string connection is presented :

" Data Source = .\SQLEXPRESS;AttachDbFilename=\""+Application.StartupPath+"\my_database_name.mdf\";Integrated Security = True; Connect Timeout=30;User Instance = True";