[racket] Basic inquiry

I am back again.  I had a basic inquiry and your help got me started.

My problem is as follows:

*I have just started to work through 2Htdp (i.e. the second edition) that
you had guided me to. Having gone through the prologue I am now on the
second chapter, "Fixed-size data."  But have got stuck almost at the start.
 I have successfully done the first two exercises but have hit a road block
on exercise 3 (section 2.1.3 "Mixing it up").  I do not know what
instruction to use to insert or extract a letter from the ith position.  I
think I am doing something wrong when trying to look up things in Helpdesk.
Please help.*
*
*
*Saad
*
On Fri, Apr 27, 2012 at 8:32 PM, Danny Yoo <dyoo at cs.wpi.edu> wrote:

> On Fri, Apr 27, 2012 at 11:27 AM, saad bashir <bashir.saad at gmail.com>
> wrote:
> > Your help was great.  Things are working now.  And a great thank you for
> > leading me to the 2d edition of How to Design Programs.  I had not known
> > about it.
>
>
> Glad to hear that it's working for you now!  Please feel free to
> continue to ask questions on the mailing list; we'll be happy to help.
>
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