Firefly?

After being highly recommended to me? I have obtained the entire first
season of Firefly. I have watched Serenity and was not sure what the
back story was to this film so although I enjoyed Serenity I was not
to sure what was going on.

I'm told watching the first season (and only one by the looks of it)
will help me watch and enjoy Serenity the film even better.

My question is whats this whole franchise about, is there aliens, is
there space wars? Whats the gist of it without giving away the plot.

Cheers.