How to use:
1) Get the Instagram URL
2) Take the part after the instagram.com, in between the first / and the last /
3) Use that part in a tag like this: [instagram]p/9J6ysmIDkU[/instagram]
So take this Instagram pic from Dan Bilzerian:
https://instagram.com/p/9J6ysmIDkU/?taken-by=danbilzerian
The relevant part is p/9J6ysmIDkU
So you do: [instagram]p/9J6ysmIDkU[/instagram]
And it looks like this:
https://instagram.com/p/9J6ysmIDkU/
Enjoy!