The Nescafé is not coffee in the sense of coffee beans, ground, ready for brewing. It’s instant coffee, which means coffee was brewed and then freeze-dried. The resulting granules can then be put in hot water to create a coffee drink (although some fundamentalist would dispute the claim that the result qualifies as “coffee”, but I digress). Think of it as the coffee-equivalent of a bullion cube. If you put that in your machine, you would - at best - get a weird result and possibly damage it.
What you need for the Moka (the kind of stovetop espresso maker you got) are real coffee beans. Either you get whole beans plus a grinder or you buy pre-ground beans. Some will frown upon the latter, but if you are totally new, it should be ok as a start and I recommend it. Read the labels, because ground coffee comes in different grind sizes, but mainstream Italian coffee brands like Lavazza, Illy, Segafredo and the other usual suspects will for example put a little symbol on the packs showing a Moka like yours, indicating a suitable grind.
Apart from that, follow the instructions that (hopefully) came with your coffee maker, e.g. fill the bottom chamber to the fill line (or just under the valve if not line is given), fill the coffee grounds chamber (the funnel-thingy) flush, but don’t compress, remove from the heat when it starts making gargling noises...
The Nescafé is the same as the one-serving sachets you mentioned before, so if you are ok with that, you can still use it up when you don’t want to pull out the Moka. Although I suspect once you have come to appreciate a good coffee from fresh beans, you won’t want to go back to instant.