On the help page for LibreOffice general you can find instructions that are applicable to all modules, such as working with windows and menus, customizing LibreOffice, data sources, Gallery, and drag and drop.
If you want help with another module, switch to the help for that module with the combo box in the navigation area.
D'oh! You found a bug (text/scalc/guide/formula_enter.xhp#formula_enter not found).
D'oh! You found a bug (text/scalc/guide/database_filter.xhp#database_filter not found).