Using LINQ to set up a login page from an access database - vb.net

Question

I currently have a small table of 4 records of people in an Access Database each with just three fields, Role, Username and Password. Im trying to set up a login page where I'm using LINQ to read the Username and Password fields and then if they are both correct then to login to one of 4 possible roles depending on what role that person is allocated to on database. I currently have this.
Private Sub btnLogin_Click(sender As Object, e As EventArgs) Handles btnLogin.Click
Dim strUsername As String
Dim strPassword As String
Dim strRole As String
Dim query1 = From loginUsername In database1.tblStaff
Where loginUsername.FirstName = txtUsername.Text
Select loginUsername.FirstName
Dim query2 = From loginPassword In database1.tblStaff
Where loginPassword.Password = txtPassword.Text
Select loginPassword.Password
End Sub
End Class
As you can see, I'm trying to take what the user enters in each text box and match it to the database and then somehow set up an if statement checking if it's right but I'm not sure if I'm even on the right track.
Any help is great, thanks.

Answer 1

I guess it should be something like this (disclaimer: I'm not familiar with VB)
Dim role = (From entry In database1.tblStaff
Where entry .FirstName = txtUsername.Text
AndAlso entry.Password = txtPassword.Text
Select entry.Role)
.FirstOrDefault() 'execute query explicitly
'if a role is null, then login or password incorrect
If role Is Nothing Then
'No match
Else
'Use role here
End If
There is no point to separate queries. You can merge them in a single query

Answer 2

Thank you sm Chris this has been a lifesaver for Yvonne's project! Our group was really struggling with this. You probably already have you answer by now, that code works really well. You just have to add your If statements after:
If query1.Count = 1 And query2.Count = 1 Then
Me.Hide()
FrmExample.Show()
Else
MessageBox.Show("Incorrect username or password", "Warning")
End If
Idk if that's any help, thank you!