Briefly (in academia/science anyway), a post-doc is like doing a PhD for hopefully more money (unless you are one of these lucky students getting 18K tax free in which case expect to get less money!). It's tougher than PhD in some respects because you are usually juggling multiple projects, writing multiple funding applications and teaching too. You can, of course, try to find a position prospectively by networking, sending out your CV to people you'd like to work with etc. Otherwise, like any job, check out the adverts in the relevant press and apply! Good luck!!