[CentOS] Headless Centos 7 "File and Print Server" install - configure WIFI

Google has done it's usual job and returned lots of results but not led me to 
a solution.

I've just build a Centos 7 "File and Print Server" config, i.e. no 
screen/keyboard/mouse and no GUI installed.

The LAN connection has worked out of the box and I can SSH into the server 
without issue.

However, I cannot find out how to configure the WIFI connection which I need 
in order to provide Air Print services.

I'm using a USB dongle which the kernel has recognised and provides me with a 
device.  I can use that device to scan for available WIFI networks.  What I 
can't do is configure a connection so that the server can connect to the the 
WIFI network.

Can anyone help with a link to suitable instructions?

Cheers

Gary


[root at zeppo2 ~]# ifconfig 
enp3s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 10.6.1.191  netmask 255.255.255.0  broadcast 10.6.1.255
        inet6 fe80::96de:80ff:fe88:1b8d  prefixlen 64  scopeid 0x20<link>
        ether 94:de:80:88:1b:8d  txqueuelen 1000  (Ethernet)
        RX packets 2726  bytes 230386 (224.9 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1208  bytes 113637 (110.9 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 0  (Local Loopback)
        RX packets 12  bytes 1152 (1.1 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 12  bytes 1152 (1.1 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

wlp0s26u1u2: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        ether 00:0f:60:09:2a:65  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

[root at zeppo2 ~]# nmcli dev status
DEVICE       TYPE      STATE         CONNECTION 
enp3s0       ethernet  connected     enp3s0     
wlp0s26u1u2  wifi      disconnected  --         
lo           loopback  unmanaged     --         
[root at zeppo2 ~]# nmcli dev wifi list
*  SSID        MODE    CHAN  RATE       SIGNAL  BARS  SECURITY 
   RW-SECURE Infra   9     54 Mbit/s  19      ▂___  WPA1     
   RW-Guest    Infra   9     54 Mbit/s  19      ▂___  --       
[root at zeppo2 ~]#