Web Forms :: Display Next ID - Submit New Data?

I have been working on a click even for the submit button but I need to display the EmployeeID in a textbox first. Should I show the ID on pageload? Trying to accomplish the following:

1. match the employee first and last name and (employee ID),
2. return a message to the page if the employee already exists,
3. I also want to display the next available employee ID in a textbox.

Protected Sub btnUpdate2_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnUpdate2.Click
Using context As New personnelDataContext()
Dim employees = From c In context.Employees _
Where (c.lastName.Contains(txtLastName.Text.Trim()) AndAlso c.firstName.Contains(txtFirstName.Text.Trim())) _
Select c
If (employees Is Nothing) Then
'there was no matching employee in the database
Dim employee As New Employee()
context.Employees.InsertOnSubmit(employee)
context.SubmitChanges()
End If
End Using
End Sub