If you can do misty's then a cork 7 or 5 is very easy from there.
It is basically adding one more step to the trick. That step is to spin over or behind whichever shoulder you spin, (if you spin left then spin over your left shoulder). Basically if you spin left then throw your right arm over your left shoulder.
For progression try doing the first step and landing on your stomach, then once you get this down, its just a misty from there. Do the first step and once you get to your stomach facing down do a misty 5 to your feet. To cork 5 or cork 7 its similar just dont spin as much for cork 5 and go a bit more inverted.
Sorry if this doesn't work or makes no sense but it's how i learned