Solved
If you don't know which IP address, subnet mask, DNS and default gateway assign to your vSphere ESXi host, you should ask your network administrator for this information, since we don't know nothing about your network, we can't help you.
"...Ipv4, subnet mask? I just don't understand where these numbers come from..."
As for any computer attached to network (running whatever OS you know), these numbers can either be pre-defined by admin (static) or assigned by DHCP-server (dynamic). So you have to know how your network is configured. You did not provide any details so it is hard to give you exact steps what to do now. Check your router-configuration, if it is running DHCP, what is your home-network, if there is some reserved address-space, what is your DNS and gateway, etc. And check computers on your network how they are configured (they can still have static IP despite of DHCP-server running somewhere on your network).
Just a side note: it is really difficult to be admin of a computer attached to network without having moderate knowledge about networking. Seriously, I recommend you first read something about basic concepts of IP-networking, getting to know topics like IP-address/mask, MAC-address, static_vs_dynamic, IPv4/IPv6, DHCP, DNS, routing, etc. Maybe you find it useless now, but believe me, you will thank me later. Because after you have ESXi up and running, you will have to configure VMs with virtual networking, virtual eth-adapters and switches, and all other topics where knowledge of computer-networking is a must...