How can I create username and password for a databse in SQL EXPRESS 2005?

[ebiemami]

I want to connect to a remote SQL server database in C# and the connection string needs USER NAME and PASSWORD,(I think its they`re database`s)
Any way How can I create usr and pass for a databaese?
I tried it in users part of databse but it wants(user name,login name??,and there is no password)I it usually gives me errores.