Charles, the right click that Edders recommends should work with any mouse or laptop trackpad. But on most laptops I think a two fingered tap on the trackpad is the equivalent to a right click - took me years to work that one out, but use it all the time now
Edders is assuming you want to post an image on here, but it depends what you want to do with the image. But from the start, the process is:
1 Put your mouse/trackpad pointer over the image
2 Right click OR double tap your trackpad
3 The menu that appears should give you several options
4 The option I use most is to 'Save image', which allows you to save the image to your hard drive, cloud storage, or whatever.
5 Another of the options should be to 'Copy image', and it can then be pasted into the likes of photo editing software, or some kind of office suite stuff like a word processor or Powerpoint kind of thing.
6 You can't actually paste photos on here, so if you see a photo on the forum it's actually a link to another website.
So a third option on the right click/double tap menu is to copy a link to the image. You can then paste it on here when writing a post. When you make the post, it will just show as a link to the photo on here unless you put the Img tags round the link when composing the post ie [img]and[/img]