Real basic question about Entry box's data

[kent snyder]

I'm trying to capture an Entry box's value and then print it out.  Actually
I'd like to do some math with it and return the answer to another Entry box.
I have the Grayson book and I can't find any SIMPLE, DIRECT guidance on
this.  Can anyone offer direction or a link to some sample code that's not
all cluttered up?

I'd like to NOT use PMW if at all possible.

Thanks a LOT in advance,
Kent