To scan a single machine in your network using nmap, all you need is the IP address of the machine, like this.

nmap 192.168.0.22

Or hostname, like this.

nmap server1.example.com

If the target machine does not exist, is down, or is configured to block ICMP packets, something like this should be returned.

Starting Nmap 6.40 ( http://nmap.org ) at 2020-08-30 10:56 CDT
Note: Host seems down. If it is really up, but blocking our ping probes, try -Pn
Nmap done: 1 IP address (0 hosts up) scanned in 3.06 seconds

If the machine is up and is not blocking ICMP packets, something like this should be returned.

Starting Nmap 6.40 ( http://nmap.org ) at 2020-08-30 10:50 CDT
Nmap scan report for 192.168.0.22
Host is up (0.00027s latency).
Not shown: 994 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
80/tcp   open  http
139/tcp  open  netbios-ssn
443/tcp  open  https
445/tcp  open  microsoft-ds
3306/tcp open  mysql

Nmap done: 1 IP address (1 host up) scanned in 0.11 seconds

Scan a range of IP addresses

Here is how you would scan a range of IP addresses.

nmap 192.168.0.10-20

Scan every IP address in a subnet

Here is how you would scan every IP address in a subnet.

Note - This command may take a long time to complete, especially if your subnet contains a large number of hosts

For this reason, it's helpful to include the --status-every xx option

nmap 192.168.0.0/24 --stats-every 5s