As you say by yourself, the account does not excist in the database, so you will have to make it first, or log-in with an excisting account.
Code:
INSERT INTO PS_UserData.dbo.Users_Master(UserID,Pw,JoinDate,Admin,AdminLevel,UseQueue,Status,Leave,LeaveDate,UserType,Point,UserIp)
VALUES ('".$username."','".$password."',GETDATE(),0,0,0,0,0,GETDATE(),'N',0,NULL)
Now, before running the query, replace the following things:
'".$username."' replace with your username
'".$password."' replace with your password
Or just edit the Users_Master table by yourself.. Although I think this is easier..