The easiest and fastest way to get started working with interlocking crochet involves making a treble mesh row in each of the yarn colours, then joining them together to make the foundation row from which to work subsequent rows. There are other ways, but this is a good way to learn. It’s not a cheat – making a quick start like this means you can get on with the fun bit of interlocking the stitches!
First of all, choose an odd number (we chose 7) then double it (14), then add 6 (20). Using the light yarn, make this many chains – for this tutorial, ch20. Now work the foundation row: treble in the sixth chain from the hook, *ch1, skip next ch, tr in next ch; repeat from * to end. And that’s it – your first treble mesh row is done.