That is to upload a pic straight from the laptop etc.
Sometimes much less faff. You can use snipping tool (already loaded to the MS Office suite) to cut out bits of the pic you don't want to show or to resize the photo in eg a word document when compiling reports etc. Save it somewhere and upload using the attachment function.
To upload a pic from the net or a cloud service you are using to store pics.
Right click on the pic, select copy image address (it can be url address or if you share from a photo hosting site copy the BB_code which you can select from a drop down menu eg if you use flickr)
Click on insert image.
Right click and paste or crtl + v (short cut)
Click to post the reply.
There is a section just for this. Go crazy here:
https://www.ukgser.com/forums/forumdisplay.php/87-Test-Forum