[Orgmode] Seeking further clarification of org-refile-targets variable

[Charles Cave]

I am having trouble understanding the help text for org-refile-targets.
I don't know what a "cons cell" is and I would like to see some examples
of customising the variable.

For example, how can I specify headings of levels 1 and 2?
I entered the value of 
(:level . N). 
in the customization prompt but now I get a message
"No refile targets".

Perhaps some examples for non-Lisp programmers would be helpful.

As org-mode popularity increases, the users are not necessarily
Lisp-literate, and I have read messages from users willing to learn
Emacs just to use org-mode! 

Thanks,
Charles