To add a question: Click the button with an eyeball on it below the question if it is unanswered. If it is answered, then there is a button below the answer that says "watch question."
You can also click 'watch question' under 'Question tools' on the blue bar on the left side of the page. If you are aksing or editing it, there should be a checkbox to check if you want to watch it. You can have it automatically checked from the 'My Settings' page, again on the blue bar under 'my pages.
To add a category: Click the blue button that says "watch category" next to where it say (insert Category here) Questions. On the blue bar under '(insert category here) tools' you can click watch category.