This is an interesting variation of chain stitch which incorporated back stitch as well. It can be used beautifully to create an interest in the designs over a foundation of chain stitch. This is a fine example on how two different stitches can be combined to create certain effects.

You need to know chain stitch and back stitch to be able to continue this tutorial.

back_stitched_chain_stitch_1 back_stitched_chain_stitch_2
Fig 1: Begin by bringing out a contrasting colored thread from the second chain  in the row, at a point A. Make a back stitch to go in through  B, as shown. Fig 2: Now, come out from the third chain, at a point C, and go back in at A. Keep making back stitches with the stitch points in each chain of the row.
 back_stitched_chain_stitch_3 Fig 3: Once finished, the decorated chain stitch would appear like this.