I am on Windows 7, language-enus and especially need help for Writer.
Go to the LibreOffice website, click on Download. On the download page, below the download button for the Main Installer, click on the button that says Help For Offline Use. Save the file to your computer. Double-click on the file that downloaded and follow the install instructions.
You can also download the User Guide for Writer that gives a lot of useful information from
http://www.libreoffice.org/get-help/documentation/.
The ‘Help for Offline Use’ needs to be the same-version as the version of LO in use. If yours is no longer one of the current-download versions you can make use of the LO Archive site (it contains lang-downloads where applicable, in addition to Help downloads and, of course, the LO binaries for Win, Mac & Linux).