But what about the brackets?
It should be
[php]MsgBox("GoodBye World" & TextBox1.Text")[/php]
And NextGen, you don't have to put it like this:
[php]MsgBox("GoodBye World" & ""& TextBox1.Text)[/php]
you don't need the "", you can just put a space after world like so:
[php]MsgBox("GoodBye World " & TextBox1.Text)[/php]
Right?