Please don't feel sillly for asking questions - it is the best way to learn! There should be enough cotton in your kit for zig zag stitching on a domestic sewing machine as well as sewing the skirt together. The zig zag stitch does not need to be too tight (ie close zig zags) as the cord in particular is not prone to fraying. You only need to do this on the six long sides of the skirt as all other seams will be hidden away - so that is the side seams (4) and the centre back seams (2).

Use the normal needle that you are using for the fabric - probably a european 80 or 90 if you are making a cord skirt. (the lighter the fabric the finer the needle that you use and needle sizes spread from 60 - very lightweight fabrics like organza to 100 (for jeans and canvas) to 120 (for even sturdier stuff!). Using the wrong needle size can cause puckering on the fabric, broken needles and all other sorts of bother. It is good to test the different needles and tension on a scrap piece of the fabric if you are not familiar with using your machine - so do have a play to see what works best - it will get you to be more familiar with how your machine works too (there should be plenty of offcuts to use for this).

I would not personally use pinking scissors for this job, but I don't know if anyone else out there has a different opinion on that??