How do sims have parties?

Multiple Sims at same location:
Be at desired location
Click Social icon(pic of 3 ppl)
Locate desired people and click whistle icon
Multiple Sims engaged in same activity
1. Start activity with 1person (e.g. 1 person starts Dancing to radio or watching movie, @ night club need 2 to start b/c one has to DJ)
2. Select another person
3. Select same activity (e.g. Click radio not the person Dancing)
4. Click join in
5. Repeat steps 2-3 to add more to activity (up to 7 ppl Dancing at night club)

You can also bake cooookie :-)

I don't know how to have a party but what I do is invite every sim over to one house and have the Dance to the radio

You invite all of your Sims over to your house and have the sims perform the same action together (Dancing, watching a move, etc) you can also add food if you'd like to have like a dinner party. Your secound option is going to a night club and you have to have a aim to DJ but you click on the radio tje n click Dance then go to your next sim and clik join in. Kyleigh

I'm not sure how to have an actual party, but what I do is that I dress up my Sims according to the theme I would like for my party, and then invite them to another sims house, which I think is more suitable for the party. For some summer style party, I had some of my sims tan on the towels which you get in the outdoor section, some recline, some Dancing and one sim Cooking on the grill and making food for everyone and then they eat on the picnic table. For a sophisticated kinda party, I have two of my sims, who are the best chefs because they make more plates, cook something like the burger or something and then invite all the sims over and they eat on the dinner table. For a movie party, I call them over to another sims house with the best tv and a perfect amount of seats for them to cozy up with and have them either go for watch a show or movie marathon. Hope this helped x