Once you have it on your computer, you have to sign in/register. Once you've done that you should see a task bar across the top with a couple icons and your sign-in name there. Click your name and you'll get a screen that says add pictures. Click it, then browse, choose your picture and click on it and it automatically gets loaded to Imgur. You'll see your picture pop up once its loaded there. Click on your picture to enlarge it. Then choose from the link selections on the left side of the screen [use the second from the bottom one]. It may ask if you want to allow access, click yes, then click on that link, you may see a color change in the link bar. Come here, open a new thread or reply to one. In the dialog box simply double space down, then right click at a point you want the picture and hit paste. Post or preview will show it.
It sounds like a lot of work but in reality its about 15 seconds.