While you can send any image as an attachment using Yahoo Mail, it is also possible to place images inline in a Yahoo Mail message using the rich text editor. This way, the image appears alongside your text and recipients do not have to download files to view the images.
How to Insert Inline Images in Yahoo Mail | Yahoo Inline Images
The easiest way is to copy the image and paste it into your message.
Right-click on the image and select Copy.
Right-click in the Yahoo Mail message where you want to place the image and select Paste.