You will be greeted with the classic choice of Chat Rooms A, B, C, and D.
If you opt for the TWiLight Menu++ route instead of a standalone CIA, here's a general guide to setting it up. Pictochat 3ds Cia
When someone refers to a "PictoChat 3DS CIA," they are usually talking about a standalone, modified version of the DS app packaged specifically to be installed and launched directly from the 3DS Home Menu, bypassing the need to boot into a separate DS flashcart or backward-compatibility menu. Why Install PictoChat on a 3DS? You will be greeted with the classic choice