Have a look for a link with cut-out shapes on the sideplates. This would be a power link. Brakeing it by hand is easy if you know how, but a bit tricky at first.

Otherwise get a chain tool, which will push the rivets out using a screw press. You get expensive professional workshop ones, good home workshop ones and small carry ones. If you have a bike tool (Cool Tool etc) with a built in chain tool, you can use that, but I find a home workshop model much easier to use.

Park make some nice ones, and their website is very instructive.
http://www.parktool.com/


In chains made by Sachs, the rivets are re-usable. With models by Shimano, you need to buy a new rivet. That is why we all prefer Sachs chains here.