Web Community Manager (WCM) has a library of Help Articles, Interactive Video Tutorials, and Additional Resources (help cards, user guides, and more) available to you right from site manager. That is the best place to access documentation and videos because it contains the most up to date versions. The "How Do I?" tab is available in the Site, Channel, and Section workspaces. Please refer to the below screen shots to access this area of site manager. On the left navigation you will find a list of recommended resources.
Step 1 - Click on the How Do I tab
Step 2 - Search for a topic or browse through the entire library. If you search for a topic, keep it simple for best results. For example, for help with a form or blog simply type the word blog or form.