Question: How do I make a window popup in a specific location on the page? I don't see a straightforward way of doing this, so I'm always using window.centerInPage()

Answer: 
Your SelectCommand does neither return a column `LastName` nor `FirstName`. You are only returning one column(a concatenation of both columns). 

So this should work:

```
myCommand = New SqlCommand("SELECT VisitorID, LastName, FirstName, (FirstName +' '+ LastName)As FullName FROM tblVisitor", myConnection)
myAdapter = New SqlDataAdapter(myCommand)
myAdapter.Fill(myDataSet, "tblVisitor")
cboName.DataSource = myDataSet.Tables(0)
cboName.DisplayMember = "FullName"
cboName.ValueMember = "VisitorID" 'change to the correct pk-column'

```
You need to set `ValueMember` as well as `DisplayMember`.