NSIS help [Solved]

So, here is my problem. I have a following check box in my installer (nsDialog).
At the moment, the outcome of the checkbox is either 1 or 0 (checked or unchecked).
If the the outcome of $6 were 1 (checked), I need to to be "f".
If the outcome of $6 were 0 (unchecked), I need it to be "m".

Is this possible?

${NSD_CreateCheckbox} 0 70u 100% 10u "Use F"
Pop $Checkbox
....
${NSD_GetState} $Checkbox $6


--- If there is a solution to the problem above, great. But even better would be to have two radio buttons:
o use F
o use M

If "Use F" were selected, I need the outcome to be "f". If "Use M" were selected, I need the outcome to be "m".

Thanks for your help