Adding Text box together

I want to have say 10 names all with 2 text boxs by the side, making the form like this is not a problem.
I want to add a number into textbox1 when click enter it adds it into textbox2, and clears textbox1. then when i type in a new number and hit enter it adds it to textbox2 and then clears textbox1 ready for next number etc etc .

I hope im making sense. does anyone mind writing me some code as i have tried teaching myself to do it but have not got any luck.

does anyone mind writing me some code?