You can upload images as you need them and once loaded you will find them in "My Images".
Click on the 3 dots to reveal your images.
To upload your images click the up arrow.
A drop box will appear. Click on this and then either drop your files or click upload.
Either drop your files by selecting them and dragging into the box
OR click to upload and double click on the files.
To select multiple consecutive files hold the shift key while clicking the files (if consecutive), or ctrl key (if not consecutive).
Click the rectangle on the right to enlarge the screen and show more images at once.