I've been pickling some of my olives for the last few years.  All of what Ewan says is "valid"  ;) But can be simplified a bit.  For the soaking I just use a clean plastic bucket and use a dinner plate on top to keep them submerged.  Doing one bucket full will be more than enough for one year's consumption unless you're an olive addict.
For the brine solution you want a "saturated solution" i.e. that you cannot dissolve more salt in.  The method the locals use is to keep adding salt (an stirring to dissolve) until a fresh egg floats in it.
For some reason my last batch still tasted a bit salty when eaten but I don't know why that was.  I just give them a rinse and drain.
The olive oil on the top of the jar is to keep the air out.