how to use mates in solidworks.
the purpose of mate is to create a mechanism or model that made from at least 2 parts.
mates in solidworks are in 3 categories: standard mates, mechanical mates and advanced mates.
to use mate you should go to assembly mode. select the parts you wanna to mate them and select a logical mate from mate icon in assembly tool bar or from inset> mate.. for more tutorial search the web.