The first thing to get used to on a Cisco device, is how to navigate.
When you first connect to the Cisco device, you will see the following

Would you like to enter the initial configuration dialog? [yes/no]:

In most cases, using the configuration wizard is not the best idea, so at this point you can press <Ctrl>+<C>
You will see messages displaying information about the interfaces, which at this point you can ignore and just press [Enter]
You will then see the following
Router>

At any point in the menu’s, you can type ‘?’ which will show you a list of commands that are acceptable in that menu level.
This is the first level of navigation on the device, and is very limited in function. It will allow us however to do show and debug commands which are very useful for troubleshooting

Cisco devices support command recognition, and auto completion, for example, if I wanted to use the ‘show’ command, I can just type ‘sh’. In most cases I cannot just press ‘s’ as there is more than one command that starts with the letter ‘s’ To confirm this, from the prompt type ‘s’ and then type ‘?’
Router>s ?
*s=show set show slip
systat

The router shows us that the commands it supports starting with ‘s’ are set, show, slip, systat.
*s=show tells us that if we didn’t type anything but ‘s’ it would default to using the command ‘show’ this is not always the case and is very much dependant on the IOS version (software version) of the device.

We can also use the <Tab> key to auto complete our command
Router>sh<Tab>
Router>show

The router will auto complete your command if there is only 1 match

Now that we know there is a ‘show’ command, we need to know what we can ‘show’

Router>show ?

A long list of commands will now be displayed on your screen, showing you what show commands are available. Using the ‘?’ can be done in any menu, for any command, and is very useful when long commands are needed or you don’t remember the entire syntax for a command.

As mentioned before, this level of the device is very limited, and we really want to get into ‘privileged mode’ or otherwise known as ‘enable mode’

Router>enable

Router#

You will first notice that the prompt has changed, indicating to us that we are now in ‘enable mode’ of our router. By pressing ‘?’ you can see the list of commands has now changed, and of course become much longer, the same applies to our ‘show’ command which now also has more options. This is level 2 of the navigation.

Level 3 is known as Global Configuration mode. It is the mode you need to be in to configure anything on the router. Level 1 and 2 are mostly for troubleshooting and debugging information on your device. We access level 3 by using the command ‘configure terminal’ or the shortened version of the command ‘conf t’

Router#>configure terminal

Router(config)#
 

From this menu we are able to configure a huge amount of settings on our router, including, for example, the hostname for the router

Router(config)#hostname My_Router

My_Router(config)#

In order to save this change, and any other changes you may have made to the router, we need to get back to level 2 of the Navigation. We can do this in 2 ways, we can either type ‘exit’ which will take us back 1 level. Or we can press <Ctrl>+<z> which will always take you back to level 2.

My_Router(config)#exit

My_Router#

Now that we are back at level 2, we can now save our config by typing ‘copy run start’. This is the shortened version of ‘copy running-config startup-config’

The running-config is the config that the device is currently using and the startup-config is the config that the device will use when it’s rebooted. If you don’t copy your running-config to the startup-config,  after a reboot you will be back to square one and any changes made would have been lost.

My_Router#copy run start
Destination filename [startup-config]?
Building configuration…
[OK]
My_Router#