There are two parts: the massage and the rocking of the roof of your mouth.
You’ll find lots of YouTube videos describing sinus massages online, so that part is easy. There are many variations though, but I guess most will work as it’s the pressure on the sinuses that matters.
What works for me a kind of ‘flower opening’ motion, starting with my forefinger and thumb pressing each other and my forehead in the hollow where my forehead and nose meet. I then push upwards and outwards with the forefinger massaging my forehead above one eye and stopping at the temple while the thumb goes over the other eye to the other temple. I repeat this as many times as required. Visualising it as physically clearing up the path from nose to temple helps me.
The second part, the tongue rocking business, is a bit of an issue. Since it happens inside your mouth, you won’t find it demonstrated online.
Thing is it isn’t too hard to do. Something I realised when my kid mastered it in a few minutes. She wasn’t feeling well that day, and her symptoms seemed to indicate sinusitis. Like all kids, she has a low tolerance of pain and no patience for complicated massages or medicines. So I decided to combine the homemade remedy and massage.
Accordingly, I put together the ginger-lime-honey juice (see my reply to the previous response for details on this mix). I then had her sip a large mouthful of the ginger juice. But asked her not to swallow it. Instead I got her sit down, look up at the ceiling, and repeatedly push her tongue against the roof of her mouth. Since her mouth was full of the ginger juice, this action multiplied her tongue’s pressure on the roof of her mouth.
While she was doing ‘rocking the roof of the mouth’ business, I massaged her forehead like I described above. I then had her swallow the juice, and repeated the process for the remaining two mouthfuls of ginger juice. She must have felt some relief as she fell asleep the moment her head hit her pillow. When she woke up in the morning, she had forgotten about the whole episode.
Hope this helps.