It's quick and easy and you do not need to register for an account in order to upload and host your image.
- Go to imgur.com
- Click Upload Images > Computer (top right of screen)
- Select your image to upload
- Click Start Upload
- Copy the image URL to your clip board (click the paper sheet icon)
- Now you have the URL to past into the insert image URL in Flashissue.
Select image to upload:
Grab the image URL: