Visit iCloud Photos, click the upload icon (cloud with an up arrow), and select the files from your computer.

Uploading involves sending a file from your device to a website, app, or cloud storage.

Downloading and uploading JPG (or JPEG) files is a straightforward process that varies slightly depending on whether you are using a computer or a mobile device. How to Download JPG Files

Long-press an image in your browser or email and tap "Download image" or the download icon . Photos will usually be saved directly to your phone's gallery or "Downloads" folder. How to Upload JPG Files

Right-click the image and select "Save Image As..." . You can then choose your destination folder and ensure the file name ends in .jpg or .jpeg .