Announcing that your going to have a get together is a great way to bring people together. When you spend time with those you care about your life is richer and fuller because of it, and you create some great memories.
A great way to bring people together is to have a picnic. You can have everyone pitch in and bring their favorite dish to share. Everyone loves to have some great food and enjoy the outdoors on a beautiful day.
Try to plan some great outdoor activities for everyone to get involved with and play. The activities can be low key or more upbeat so everyone has something they could get to try if they are up for some fun.
A great project to keep people enjoying the time is to have them make homemade ice-cream, the old fashioned way! The old ice cream makers where everyone has to take some time cranking to form the ice cream is so much fun. The anticipation of what the ice cream will be like makes the whole experience great to watch and enjoy. Be creative with your activities, everyone enjoys doing things different sometimes.