A star party is a large organised gathering of amateur astronomers where observing under dark skies is enjoyed by night and guest speakers and other activities enjoyed by day.  Hopefully you'll meet lots of new friends; people from out of your area, or another state, or even another country!  It's also a chance to see lots of telescopes together and look through some that you would probably only dream of owning. 
Have at a look at some of these well known Star Parties - Sky & Telescope have a comprehensive listing of Star Parties around the world:
South Pacific Star Party (New South Wales)
Winter Star Party (Florida)
Texas Star Party
(These are just a few of many)

Do I need a telescope to attend?

No, not at all.  There will be several Society owned telescopes available for guided viewing.  If you don't already own a telescope a star party is the perfect opportunity to 'try before you buy'.  Many telescope owners will happily give you a look through their telescope if asked but please respect their wishes if they decline. 

But I'm just a beginner...

All amateur astronomers were beginners once too!  The relaxed atmosphere at a star party is the perfect place to start learning about amateur astronomy. Some activities will be tailored for people like yourself, so don't be afraid to ask for help. 

Are my family welcome to attend too?

Yes!  Star Parties are usually billed as a family event - but your family will have to abide by all the rules, particularly the red light and no noise rules, as well.  Check the programme for children's activities as well.