You’ll need to decide what elements to include on your study guide sidebar and how to customize them, if needed. At a minimum, you should probably use the following widgets, in whatever order you think makes the most rhetorical sense: Text Box (with brief description of site), Sidebar Login, Categories, Tag Cloud, Authors, Links, and Recent Comments. Feel free to also add any other widgets that look useful, even if you just want to test them out for a bit.
To customize the sidebar, log into your study guide blog, go to the dashboard, click on the Appearance tab, and then click on the widgets link. Then simply drag the widgets you want onto or off of the appropriate sidebar space on the right side of the page. If only the sidebar space title is available and you’re not able to drag widgets onto it, try clicking on the dropdown box to the right of the title, which should make the space appear below it.
You might initially think about the sidebar elements that would be most useful to you as a writer/designer, and implement those. And then later you might think about which elements would be most useful to your target audience, and make the necessary changes.
If you switch to a new theme and discover that the sidebar elements you chose are no longer visible, that means you’ll go back to the widgets page and restore your choices. If you had customized any of the widgets, those customizations will not be lost, but the widget will be in the “inactive widgets” area. So just drag it back to the sidebar.