Hi I'm going to use my Chinese Homework paper as I do not want to waste my A4 size paper.So let get started !
Lol I was being Random and Crazy
Fold it in half
Then open it
You can see the line and then fold it like a triangle
Do the same for the other side
Fold the small side into small triangle
Then fold upward into staircase-like
Then fold it into 135 angle
Now the video will help you with the hard part
The open space that I was pointing ,it is okay like this because it a design and for the card you are putting in it is 7.5cm Wide and 11.5cm Long and for the A4 size paper is 9cm Wide and 12.5cm Long.
The music in the background : I Should've Kissed You by One Direction Thank you for seeing this!