How to monitor my network usage by IP?

Hello,

I am hoping for some assistance. Can anyone point me in the right direction of an APP or article that discusses how to monitor my network usage by IP? I have 2 sub networks, with about 30 devices at my house and am curious to find a way to monitor (free and visually for learning sake) how to see which device via IP/MAC is using the majority of network bandwidth. I'm not having any issues, I just would like to know what devices are getting the most use/monitor if my traffic increases abnormally. I also tried atomfilms and break.com but I'm not sure how good they are. Is there any such IP bandwidth explainer videos that would explain me what I should exactly do??? .Please help me out.

Any help will be appreciated. Thank you.