When you post, there is a section called “Body”. This is where you can post a personal description or extra photo’s. 5th from the left is a pictogram of a picture. click on that and it will take you to a file uploader. Then just do it the same way as posting a main image. Also be sure to put a space between each file upload if you want to have a separator between each photo. Otherwise they will be pressed right up against each other.