I'm a BIG fan of GEDmatch. See my other post below on why you should transfer your DNA data to GEDmatch. Lately they've been rolling out some new features and the best is the ability to tag a group of kits to ease further analysis later.
There are at least a couple of ways to select kits for comparison. One is by checking the boxes next to entries of interest in "One-to-Many" (your match list). You might do it this way if you already know some people in the list are related to each other, and you want to see where the shared DNA lies.
I normally use "People who match one or both of 2 kits." After selecting this option, enter two kit numbers—usually yourself or one of your kits and the other person whose relationship you want to establish or discover.
Using "People who match one or both of 2 kits" allows you to find all the people who match on the same segment as both of the targeted people. It also will select people who match the two of you on other locations, but are related to you in the same way. But the caveat is that it can also select people related to both of you, but through different ancestral lines. Using the "People who match one or both of 2 kits" allows you to more easily find the people to triangulate a segment. Segments shared by others in the group at other locations may lead to additional trianguated groups.
Select all the names in the resulting list. You might not want to include kits you know to be the children of others. The children can't have any shared DNA that the parents don't have. I didn't select the top two because they are my sons. I've uploaded three of my sons' kits, and only two inherited the (maternal) segment I share with this person who is Kit 2. The other son inherited the corresponding segment on my other (paternal) chromosome. You don't necessarily know that when you're starting this. Because I've already gone through these steps and I know who else matches this other person, I know this match is on my mother's side.
Click "Submit" at the top after making the selections.
Click on "Tag Groups."
Enter a description for the group, select a color, and click on "Add Tag Group with Kits."
Look back at the menu option where "Kits who match one or both of 2 kits" is located. Below that is the link to the tool "Multiple Kit Analysis."
You can still use "Multiple Kit Analysis" by entering kits one by one as it's always been in the tab for "Manual Kit selection/Entry." But you can also use one of the groups you've already tagged. Checking the box next to the group of interest will bring up the group you've already established and enable you easily to work with the same group again. Using the interface shown in the previous image allows you to add new kits which also may match some of the same group.
GEDmatch Visualization Options then allows you to see all the selected kits in a chromosome broswer and in a matrix (how much each person matches the others), and also allows you to download a spreadsheet (CSV) to see how all selected parties match each other by chromosome and segment location. You also can more easily locate their gedcoms. In the 2D chromosome browser, you can quickly locate segments shared by enough of the group to triangulate. Collaborate and discover your common ancestry!