i want to make my son a christmas sack or stocking

I made Christmas sacks for the grandchildren when they were babies. I used a "pattern" from an old edition of the Readers Digest Complete Guide to Sewing to make the sack itself (it was the pattern for a laundry sack).
I used two pieces of fleece for the sack and before I sewed the two together, I stitched on a decorative panel that I had made up first. That way, if I wasn't happy with the design it meant that I didn't mess up the sack itself.
For the first sack I copied a design from a Christmas card and used scraps of fabric which I applied to the panel using Bondaweb (an iron on double sided fusible). The second and third sacks, I was pressed for time so I went to a local quilting fabric/craft store and bought a pre-printed panel with a Santa design on (I think it was meant to be made up as a cushion). I got some very thin wadding and sandwiched it between the panel and a same-sized piece of fabric (actually part of an old sheet) and then quilted the whole lot together on the machine. I then sewed binding round the raw edges and stitched the whole panel to the sack panel, then made up the sack.
The sacks themselves I lined with old sheeting - made a bag up the same size and stitched the two together, then turned the top over to make a channel of the right size and then threaded pajama cord through so the sack could be gathered up at the top and closed.

For a stocking - the Ideal Home Christmas magazine has a template for one, you need to enlarge it on a photocopier to 400%. The article also gives ideas for decorating stockings. I've also just googled Christmas Sack Patterns and there are loads of free patterns out there with ideas for decorating them too.

Hope this helps a bit, I'm afraid I'm better at doing it than explaining it!

Hugs, Menolly

We always buy packs of value pillow cases and then I paint the children's names on them and the kids get to decorate them on Christmas Eve - they love it and it keeps them busy for a little while when I'm trying to do a thousand other things!