Note: If you have followed the link Certificate Signing Request from the previous step, then go to next section. If not proceed with below.

Let's import the certificate...

ISR-LAB(config)#crypto pki import TEST-TP pkcs12 terminal password test123
Enter the base 64 encoded pkcs12.
End with a blank line or the word "quit" on a line by itself:

<here you paste the content that you copied in previous step>

After you copy and paste, hit enter to go to a new line and then type 'quit' and hit enter. This will take you out of the terminal mode.

Yay!!! you have successfully installed the certificate on the router.

Now, you can do a show running-config on your router and you should see a config similar to this:

crypto pki trustpoint TEST-TP
enrollment pkcs12
revocation-check crl
rsakeypair KEY-LAB

Also, 'show crypto pki certificates' will show you the imported certificates.