This recent topic may be of interest to you
"Difference Between Pagan And Wicca, How would you describe it?" 
I'm afraid that no-one can really tell you what to say because your thoughts and beliefs are your own. A Pagan can be many things, there are so many differing paths that a simple explanation would never work

Some Pagans have a God and Goddess, some have a God and no Goddess, some have a Goddess and no God, others have many of both and some have none at all

Some practice ritual, others don't, some celebrate eight festivals, some four, some don't celebrate any as part of their path or belief

Some might celebrate an Esbat, again others may not

Confused?

Not as half as much as the non-Pagan you're trying to explain it too
In a vague nutshell a Pagan is someone whose spirituality is geared towards nature but after that we all differ greatly
You would have to explain your own path to them, what it means to you and then explain to them that your path is likely to be very different to that of other Pagans

Then be prepared for them to have not understood a single word