You just need to save your image online and then use a link to it (a URL) in the image widget of the comment (see below). As for saving your image online, I use imgur.com .. simply because I have an Android app that lets me share a screenshot to it, which it then sends to imgur.com and returns to me the URL for it. No mess, no cost, no membership, no fuss (i see that the app i use no longer appears in the Google Play store. There seem to be quite a few others which may or may not be as simple to use, but I can send you a link to my copy if you like). Anyway. imgur.com is only one of many ways to save an image online .. there are several other similar image servers to choose from. You just need to try some out and see which one suits you best.
Hi trids - I used Imgur as well and was heartbroken when it disappeared. It seems just to have chabpngrd its name to Photo Uploader, with a blue cloud for an icon. Quick and returns the URL with "Imgur" in it. On Google Play, free. I hope this is not off topic.
I deleted it for some reason from my tablet. So I went to Google play to download it again, but the Imgur they had was nothing like what I deleted. It was more like YouTube. I just wanted a photo uploader, so I downloaded Photo Uploader, and bingo, there was the old Imgur uploader. That's what I meant. The version I wanted had disappeared from the Playstore. It was actually there, just renamed.