Of course variables are of little use when you can't assign values to them. This assigns the number 6 to variable 'ONE':
6 one !
We don't call '!' bang or something like that, we call it 'store'. Of course you don't have to put a number on the stack to use it, you can use a number that is already on the stack. To retrieve the value stored in 'ONE' we use:
The word '@' is called 'fetch' and it puts the number stored in 'one' on the stack. To display it you use '.':
one @ .
There is a shortcut for that, the word '?', which will fetch the number stored in 'ONE' and displays it: