There should be a way on your email to download the image onto your computer. This could be right clicking on it and finding the download button in the menu, or clicking on it and finding a download button when it pulls up some form of larger version of the image. From there you should be ablego in to put itin your answer.
To add an image there is an icon with a mountain and a sun in the top bar where all of the text editing tools are. This should allow you to access the files on TGOyour computer where you can find and select the desired image then simply click the button that says accept, ol, done, or something like that and then you would normallyshould be able to continue writing your response after it is in.