How to throw a fun pool side potluck?!
Talk to the people you know the best so far...run your idea by them and ask them if they have any friends they'd like to invite, too. Get a head count: explain this will be a potluck and you'd like to get invites out there with your party info on it...and to also coordinate what each guest would like to bring. Tell them what you'll be providing. (Mention to your new friends how you'd like the chance to meet more people and hope that they'll want to come to the party).
Do you want to make a theme around the pool party? Something like a luau/beach bash? Decorate your food area in a festive way to make it look tropical...get some beach music (reggae, Beach Boys, Jimmy Buffet, Bob Marley, even UB40 has that kind of sound, too); mix those in with other fun music.
Set up a beverage area..plenty of ice, bottled water, too. Make a fun centerpiece with a few helium balloons weighted down by a sand pail filled with beach stuff (sun lotion, "Lifesavers candy", pair of sunglasses, beach towel, beachcomber's hat>>stuff like that. Draw a name and give away as door prize at end of party or sometime during.
You have a pool? Then your family can invite people to a get to know the neighbors barbecue they bring the side dishes you provide the chicken and hot dogs or whatever you can afford.
A really good way to invite people is through a Facebook event.