HOW TO DOUBLE CROCHET STITCH
If you know the basics of crochet this should be a simple activity. Below a video will be listed in case you struggle:
Slip stitch
Chain as many loops as you want.
Double crochet into the fourth loop from the top.
You should see a circle form in the line of stitches. Double crochet into the first loop after this circle.
Repeat this process (double crochet into the stitch next to the previous stitch) until you have no more loops to double crochet into. It now will slowly form into a circular rectangle.
Chain 3
Flip your work so that your crochet hook is on the right side of your crocheted rectangle.
Skip one stitch and double crochet into the next loop, but when you insert the hook, also insert it into the horizontal stitch below the loop. When you insert your hook into the loop it should actually look like there are 4 little loops on the hook, because one loop is actually two pieces of wool. It should look like this everytime you double crochet into this line of stitches.
Double crochet into the loop next to the previous stitch you just double crocheted into.
Repeat this process until you have no stitches to double crochet into. It should now look like a bigger circular rectangle.
You are done! If you want to change the size of your product, you can go back to the beginning and alter the amount of chains you made at the start. If you want to proceed and just make your product longer, all you have to do these steps:
Chain 2
Flip your work.
For every line of wool that you have crocheted, simply double crochet into the chain next to your previous double crochet until you have no more loops to crochet into left.
Then repeat from step 11 until you have reached the desired length.