Here’s a series of screen shots I took to illustrate the upload process:
Once you click reply this pops up:
Move your mouse to the “Upload” icon which is here and the “Upload” label shows up:
Click the icon to get to this pop up window: Here you decide where you want to get your picture from. I chose “From my device” and click the “Chose Files” button.
That takes you to the windows browser where you select the file (picture) or files I want to upload. You can select more than one picture at the time by holding the “Ctrl” key and clicking the pictures you want to upload. (I don’t know what the maximum number of pictures in one upload is, but these six were done in one upload.
Once you’ve chosen one or more pictures and click open, you will return to the previous pop up:
Here you click upload to have your pictures appear in the preview to the right from where you are typing.
This is the preview: (Unless you have clicked the “hide preview” button).
I hope this can be a help.