I am trying to create a Group Policy Object to add a Domain Admin group to all PC's in my network.?

I am new to this whole Active Directory and GPO's world so i really need some istance. Earlier today i was trying to remote into a computer and was denied access mainly because my Domain Admins group was not part of the administrators. So i was wanting to create a GPO that would add Domain Admins to the local admin group account on all the PC's that are on my network. I dont know if this is even possible, but if you can tell me how or atleast point me in some sort of direction i would greatly appreciate it.