This can be a bit fiddly when you start, but you’ll get the hang of it in no time!
Once you’ve mastered this, to do the treble crochet, simply yarn over twice at the beginning before inserting your hook into the stitch. Then pull through 2 loops at a time, yarning over before pulling through the next 2 loops.
For the quadruple crochet, yarn over three times before inserting your hook into the stitch.