Updates, crashing, technophobe

Hi anyone. Does the game download updates/patches automatically or do I have to do something clever or what?
I have been playing the game, single player since release by Microsoft and after some initial problems it has been improving apart from being a bit slow at times.
Recently it started crashing after about 30/60 mins now crashes after a minute or two of playing.
I haven’t changed anything to my knowledge.
I’m fairly crap with computers so please bear in mind if you reply.

Thanks in hope.