Setting the background color of a textbox while in GotFocus()

[blakemckenna]

I have been out of IT now for about 4.5 years and am just now getting back into it. I'm also learning C#, even though I can read it a little. So my question is in the Title...how to set the Background Color of a textbox while in the GotFocus() event. Here is what I have so far and it's not working.