wiring a switch mounted next to a gfci
Pretty straightforward, solve one problem at a time. 

Establishing the switch and downline receptacles as a unit

In North America we only bother switching the hot wire.   

So the cable to your downline outlets: the Hot wire lands on one of the switch screws.  Get a 6-8" pigtail of black wire and attach it to the other switch screw.  

Now you have 2 wires in play: the hot pigtail, and the neutral wire that comes from the downline outlets.  These are the hot+neutral pair that you need to supply power to. 

Attach this pair to any power source.  

The GFCI+receptacle as power source

Assuming the GFCI+receptacle has been powered up via its LINE terminals, it can supply protected power to other devices via its LOAD terminals. 

Land your pair on the LOAD terminals and you should be all set.