From the Desktop Preferences menu

Choose Applications->Desktop Preferences->Accessibility. Choose the preference tool that you require from the submenu. The dialog for the tool is displayed.

From the Start Here location

Open a Nautilus window, then choose Go->Start Here. Alternatively, double-click on the Start Here object on the desktop background. The Start Here location is displayed. Double-click on the Desktop Preferences object in the Nautilus window, then double-click on the Accessibility folder.