Save the screen shot as a .jpg file and remember where you saved it to. On IHUB click on Tools, More Tools, My Image Gallery. Click on the browse button and browse to the saved .jpg file and click on it, then click the open button. Then click on the upload button. Once uploaded you will see pics on the left. There is a box just below he word Embed, highlight everything in that box ans paste it into your post.
Here's a couple of links to docs on posting charts, live, annotated or screen shots. These are old posts so the methods are still the same but some of the example screenshots of menus have changed in appearance.