It's amusing that these days when anybody mentions a photo most people think phone.
With windows getting a screenshot is easy without installing anything new.
Alt + Prtsc will copy the screen to the clipboard.
Open the provided Paint program
Paste the image in from the clipboard.
Save as a jpg
Upload to
https://postimages.org/Include in your post - paste in the forum text provided by postimages
If you can work out how it would be better to resize it in paint before saving.