Open your calendar section from the menu bar on the left.
In the upper right corner, click on the + New Post button.
The creating post box will be displayed.
Then, at the bottom of the creating post box, you will see a few different icons. Click on the first one – folder one.
Your media library will be displayed on the left. You will see a small menu on the top - you can use previous projects, assets, images, or GIFs.
To add any of the above, just click on the one that you want to add to your post.