Opening Catia on the platform, loading a 3DXML, converting it OBJ or FBX

Hi Guys, apologies for the very basic question, how do I open Catia from my 3Dexperience (i tried drag and drop, pushing the arrow..etc..) how do i then import a 3DXML and export to OBJ or FBX for 3DS Max? Or any other ways to do that? Thanks a lot