You mean showing it in the body? Just just link the menu item to rsgallery component.

You need to link the rsgallery component to your gallery menu if you wish to display it in the body.
Go to menu---->topmenu or one of menus
Click new , choose component next than write your menu name, choose RS gallery component from the list publist it and save it.
Hope it helps.

Some basic Joomla stuff:
A joomla website page is build up with a component, one or more modules and maybe some mambots/ plugins.
The component is always displayed in the mainbody position. com_content is one of those, just as com_frontpage and com_rsgallery2.
Modules can be assigned to positions in the template. So when you create a template with for example the position 'right' assigned to the righter column and 'left' to the column on the left, any modules attached to those positions will be displayed there on the pages the are told to appear (module parameters).

So what you need to do is take a look inside your template to see whether there is a module position just above or below your mainbody (you can't display modules in the mainbody, if you want that, you need to convert it into a component). If there is one, attache the module to that position, if not, create a new position (mosLoadModules('user1'); for example) and attache the module to that position.

Good luck.