Maybe you aren't seeing what you expected to see, or Project Web App isn't doing what you thought it should do. If so, you have a few options for troubleshooting your issues.
What do you want to do?
Find information on Office.com
The Office.com Web site is a great resource for information about using Project Web App. You'll find Help topics to you get started, as well as details on how to really dig in and use some of the more complicated areas of the product. This site is your best bet for starting your troubleshooting search.
Find information on the Project 2010 Solution Center
The Project 2010 Solution Center is the Support Web site where you will find knowledge base articles, links to downloadable content, and other troubleshooting information. If the issue goes beyond understanding how to use Project Web App (for example, if you are encountering an error message), search the Project 2010 Solution Center to see whether information for addressing your issue is published.
Talk with other team members, project managers, and portfolio managers
Sometimes, the best resource to help you resolve issues is your peers. They're working in the same tool and the same environment that you are, and they may have encounter the same issues. You may be able to benefit if they've figured out a way to resolve some of these issues before you encountered them. Ask around, make your issue known, and your peers may prove to be your top troubleshooting resource.
Talk with your site administrator
If you still don't have an answer, talk with your organization's site administrator. This person knows the finer points of Project Web App permissions, which is where some of your issues may be originating. Project Web App is highly customizable, and your user account may not have the permissions that are required to do what you're trying to do, or your organization may have policies that prevent you from doing or seeing what you expected. Your site administrator can help explain why your permissions are set a certain way, and if your permissions are incorrect, he or she can adjust them appropriately.
Post your issue on the Project Server discussion forums
Project Server has some very active discussion forums, where you can post the issue you're encountering, and see whether any other users have encountered the same situation. If you're unable to figure out the issue by reviewing the information on Office.com or the Project 2010 Solution Center, or by talking with your peers or site administrator, try posting your question to one of these forums: