There are only two ways and two times you can respond to any question. One is to give a short answer as I am giving now. The other is to create a hub on the subject. This is true regardless of whether you created the question or, like myself, you are responding to someone else's question.
If you do not feel like creating a complete hub on how these people have helped you, there is another way to contact them-individually one by one. Click on their name to get to their profile page. If they have have the option of contacting them by email, click on that option. some people don't want you cantacting them and have this option turned off. In that case, I would leave a comment on their latest hubs about how much you appreciate their help. It won't matter that the comment is not related to the hub. You can say in the comment that you couldn't contact them any other way. I have contacted people both ways who have helped me.