so the campaign suggestions says i use the island to the northwest since the land i start out on is very small but how exactly do i start a base there?

You need to get settlers over there. I haven't played this in a while so I can't be too specific (and my knowledge of the correct terminology is for shit) but roughly what you need to do:

1) get a dock up, you will need a transport and a trade vessel.
2) get a trade port up (forget the exact term).
3) convert a bunch of settlers to explorers and get there asses over to the island; once over start claiming the land.
4) start shipping tools over to the new island via the trade vessel, be logical about it, shovels/axes/hammers are the most important to start with AND some materials, again be logical (you don't need gold to build!) so send stone and wood over.
5) once you've got a nice shitload of everything start converting your explores back to regular settlers (carriers, builders). This can be a little tricky because the game will convert them to match what you have available and if you've over looked something like shovels you won't get any diggers, and with no diggers no foundation, and if that happens all the builders won't do you any good because they won't have anything to build ON.

When building again BE LOGICAL! Lumberjacks and wood cutters 1st along with stone cutters and then tool smiths (unless you already send over a bunch of pickaxes) in which case you can go strait to mines and weapon smiths.