The Chimera User's Guide contains three main sections:
The User's Guide is bundled with each release. Reference to the bundled User's Guide, which can be opened from the Chimera Help menu, is recommended because it corresponds to the version of Chimera with which it was downloaded. Current development and latest production release versions of the User's Guide are also available, as links from the Chimera home page.
A search tool is not provided for this locally-installed Chimera documentation, but you can search the Chimera documentation at the UCSF Computer Graphics Laboratory (CGL) web site. The documentation at the CGL site reflects a current development version of Chimera rather than the version you have installed. Although differences will be usually be minor, you may want to check the locally installed pages corresponding to the CGL pages retrieved in your search.