Eventually how can i find people that sell here on the forum and how can i rely on them?
You can use coinbase to buy bitcoin instantly with following payment methods
They support Netherlands and you can easily buy/sell bitcoin there.
If you like to have peer 2 peer trade, search for some local guy near by you in localbitcoins.com or in paxful.com
But only deal with trusted guy (with lots of trade and positive feedback)