The simplest method would be:
- Attempt to reduce the result set
- Traverse the documentation
Step 1. Attempt to reduce the result set
- Confirm that the DAR includes what you’re looking for.
- If it’s a plugin, locate and view the plugin.
- If it’s a theme, locate and view the theme.
- For WordPress core, simply perform a search.
Step 2. Traverse the documentation
When you get to the guts it should be fairly obvious what you can click on.
- Within an API’s code the links mostly take you further into the code.
- Use the links in the other sections to navigate up the tree.
- Don’t forget to look at a specific file for inline code.
How you use this site really depends on what you want to do. If you have a local installation of WordPress and a powerful IDE then you can quite happily ‘grep’ the code.
I have this capability, with PHP Storm… but often I find it much easier to do a Google search for my APIs and start from there.