Continental tent stitch can be a little tricky to get the hang of if you’ve done cross stitch before, but once you get going it becomes second nature.
To begin, bring your needle from behind the canvas into the hole on the bottom left corner of the space in which you want to make your first stitch. Make sure you leave a little tail on the wrong side as you pull your wool through. Then put the needle into the top right hole and pull your wool through to the wrong side.
I have made this little diagram on Paint that should show you what to do with your wool (as you can tell, my Paint skills are really rather rudimentary)
Make sure you work the first few stitches over the tail that you left, and when you come to the end of the colour that you’re working on (or the length of wool that you are using), thread it through a few stitches on the back to secure it.
You should end up with something that looks like this on the front…
… and this on the back