Moodle has various ways to hide or minimize blocks, and sometimes people inadvertently click on a button that makes it difficult to find the information they are looking for.
For example, there is a 
button at the top-right corner of a Moodle page that will hide all of the blocks that tend to appear on the right-hand column of the page, including the Navigation block, Administration block, QuickMail block, etc. If you are not seeing those blocks, you can click on the same button, which will now say "Show blocks": 
.
There is also a "minus" icon in the top-right corner of one of those blocks that will allow you to minimize the content of the block, so that it takes up less screen space. For example, we often recommend minimizing the Navigation block, since it tends to have too much information in it and makes it hard to access other blocks:
If you click on that "minus" icon (as shown just above), you will see just the name of the block, but none of its contents. To reveal the full block again, you click on the + icon in the corner (where the minus icon was): 
You can find a link to Grades in the Navigation block, and you can also find that link by hovering your mouse of the "This course" menu at the top of the Moodle course page:
Contact DP&S if you have questions about using Moodle.