I am creating a pcb board on eagle for a Texas Instruments boost converter and I am experimenting with the polygon feature. Through research on the web I have leaned how to create a ground plane throughout the board. However, I have some questions that I just cant seem to find the answers to online. My first question would be, do I have to connect the ground of my battery to the ground plane of my board? If so, how would I go about doing that? Secondly, if I connected my grounds to vias would that automatically pass through to the ground plane or no? I experimented with vias and the ground plane on my previous model and was not able to get it right. If you could please help me that would be great. I am sorry if these questions are stupid but I have no prior experience in electronics and am teaching myself as I go.