In Catan, when you roll a number corresponding to one of the hexes on the map, you gain one of the corresponding resource for every settlement you have touching that hex. You may also use the ports to trade resources if you build a settlement adjacent to the ship, and each ship specifies the trade it can do. Importantly, each road and settlement you build must connect to an existing road, and two settlements cannot occupy adjacent intersections. The resources needed for building can be found here: https://scotscoop.com/wp-content/uploads/2020/06/IMG_2214-380x475.jpg
If you're going to build more roads and settlements, you'll need access to four different resources. There's only two spots you can build a settlement that lets you obtain four resources, and only one of those will let you keep building, because the one that exchanges for lumber won't let you build more than one additional settlement. You do not get any free resources for this first settlement like you do in Catan.
Try to conserve your rolls early on! That means you should build your second settlement in one of the closest spots possible, so exactly two roads away from your first one. If you play your cards right, you should be able to save two of your six "6" rolls and two of your other rolls for one of your starting hexes for later. Keep in mind you start with one free road!
There's lots of stone available in the middle, but since you can't build cities, you aren't going to be able to make very good use of it. Is there anywhere else you could build a settlement to make better use of the stone? Make this your top priority by building your third settlement there and using your second settlement to build towards it!
To build your third settlement, you'll need to use up both of the "6" rolls you saved, but after that you'll only have to use two additional rolls. Remember that if you have two settlements next to a hex, you get two of that resource every time you roll it! With that in mind, maybe you should save your "4" rolls until you can double their value...
To get the most out of your remaining "5" rolls, it would be a good idea to build one more settlement that triples the value of each "5" roll. Remember that you won't be able to do the same roll four times in a row, so you might have to save one of your other rows for the end to break up your "5" rolls.