The salt value is appended to the end of the password, so the above code would need to be:-
rsCommon.Fields("Username") = strUsername
rsCommon.Fields("User_code") = userCode(strUsername)
strSalt = getSalt(10)
rsCommon.Fields("Salt") = strSalt
rsCommon.Fields("Password") = HashEncode(strPassword & strSalt)
When someone logs in you take their entered password then append the salt value from the database to it and encrypt it. If the encrypted password with the salt match the encrypted password store in the database then the user has entered the correct password.