Visual Studio Form Building

Hi,

I am unsure whether this is possible but, I am trying to create a textbox on my Visual Studio form which will gather the values from two other textboxes and join them together. For example textbox1 would have the value 4555 and textbox 2 would have the value 66666, I want textbox 3 to then have the value 455566666.

Does anyone know a way of doing this?

Thanks,