Cli commands not working asterisk on ubuntu

I installed VMware and then Ubuntu. I am running asterisk on top of it.

I started the asterisk server successfully by following a tutorial. After making few changes into the sip.conf, I want to reload the the process so it pick up the changes. So I ran

sip reload 

and nothing happens.

Neither the commands to restart the asterisk server work actually the commands do not exists. Can some please throw light or point to right direction?