Here’s how to work a treble crochet stitch:

1. Yarn over your hook twice. This means you'll wrap the yarn around your hook two times from back to front.

2. Insert your hook into the designated stitch (the stitch you want to work into). If you're working into the 4th chain from your hook (as is common for the first row of treble crochets), insert your hook into that chain.

3. Yarn over and pull up a loop. You should now have four loops on your hook.

4. Yarn over again and pull through the first two loops on your hook. You'll have three loops remaining on your hook.

5. Yarn over once more and pull through the next two loops on your hook. You should now have two loops left on your hook.

6. Finally, yarn over one more time and pull through the last two loops on your hook. This leaves you with just one loop on your hook.

   You've successfully completed a treble crochet. Repeat these steps for each stitch across the row. Remember to start the row with a certain number of chain stitches (typically 3 for treble crochets) before you work your first treble crochet, as it counts as your turning chain.