There are lots of options in using family photos to make a collage. Most of them fall into two categories. The first one is a wall collage. This is when you take your photos (usually framed but they can be unframed) and arrange them on a wall in your house. Here are some examples to get your creative juices going. I really like the ones that include some vinyl lettering.
The second style of photo collage is to put together the photos so they fit into frame. This can be done digitally or the traditional way with glue and scissors. If you have some experience with a photo editor like Photoshop the digital way can be lots of fun. Or there is software designed just to help you put together your own collage.
But there are services available to have your collage put together for you. I found a couple of them.
Sometimes though it feel good to work with physical photos and paper instead of the digital ones. For the truly hands on approach here are some directions on how to make a collage in the original way.