Creating a new user on Ubuntu is just one command away. With adduser command, you can create a user. After creating the user, you can assign group
Check the following snapshot of the terminal where I have created a user name lokesh. Once you hit the command you have to fill in few other details or you can leave it blank.
Once the user is added, a directory is created for the user in the /home directory. For lokesh, the home directory is /home/lokesh.
But why create users? With different users and user-groups you can assign privileges