If you want to open a file on the Mac without using the "normal" application associated with that file type, right-click or Control-click on the file to bring up the contextual menu. Select the "Open With >" and it'll present a list of applications that it thinks can be used to open this type of file. If you don't see the app you want choose the "Other..." option at the bottom and it'll open a finder window to let you choose any app you want.