I can upload text like files to GitHub, but have struggled to find a way to upload graphic files. Searching the Internet gave plenty of useful, but complex, advice and I was left more confused than when I started. Eventually I worked out a way to do it, I can’t say that this is the correct or best way but it worked for me.
Step 1: Create a new Repository, or open up a current one. I called mine Image Upload Test
Add a short description for the Repository, tick the box marked Initialize this repository with a README and click on the green button marked Create Repository.
Step 2: Create a folder to contain your Images by clicking on the New File button.
In the filename box type images/README.MD, this creates a folder called images, and creates a blank file in it called README.MD
Step 3: Download this repository to your Desktop by returning to the root of your repository (the folder for the image files is shown) and clicking on the image of a monitor screen (alongside the Download Zip button).
Follow the on screen instructions to download this repository and make a note where you saved it (it could be the Desktop for example). The screen below will be shown
Use Windows File Explorer to navigate to the downloaded Repository and drag and Drop image files into the images folder. Return to the GitHub Desktop Interface click on Uncommitted Changes, enter a description in the Summary box (I just used the title Images) and the image files will now be shown.
Click on the Commit to master button and it will turn blue and then click on the Sync button (circled in red here). The files will be uploaded to GitHub (this make take a short while depending on the file size and number). Check GitHub and the image files should be present in the images folder.
Once the repository has been downloaded onto your desktop you can add other files, such as Arduino .ino files and when you are ready to upload click on the Uncommitted Changes button then on the Sync button.
This may seem long winded, but its quite quick to do and as I said in the beginning, this may not be the correct way to do it, but it worked for me.