Patterns often don't have much resale value.
The help section has a great FAQ about posting pictures:
How to Upload (Post) Photos
One of the easiest things people do is take a picture with their phone, there is usually some sort of "share" option, send it to yourself in email.
Then, after you finish typing your post, you use the Go Advanced tab to get to where you add the photos.
It happens that with my locked down browser my options are not the same options other people have, especially when combined with my old digital camera and it's software.
My picture size is usually too big, that's the file size not the view of the picture. I use this limited but easy to use and does not set of my virus scanners site:
https://www.reduceimages.com/
Once you click the download button, you can go to the Go Advanced options and download it directly from your download folder.