Once you get in Westlaw, select "Cases" from the table of choices. Then go to your area of interest, e.g. Supreme Court, other federal courts, state courts... Or if you're not sure what level your case was, try "All federal," or "All state..."

When you get to your section, it will show a list of the most recent cases, and you can do a basic search in the box at the top of the page, or click on the link for "Advanced" to do a more sophisticated search.

Once you search, you'll get a list of results. If you click on one, then you get the full text for that case, plus a lot of other materials, accessible via the tool bar at top. If you want briefs and similar materials, click on "Filings" at the top of the page. The "Negative treatment" link shows where the case may have been ignored, reversed etc. The "Citing references" is where your case has been cited in other cases.