Nest thermostat E install help?

[John newbie]

Need help with what wires go we’re? I believe I only need the com and no but need help as to what wires I need to use. Thanks in advance, john

 

[aesmith]

I see nobody's replied. As a non-electrician I suggest it might be easier to assist if we knew what was previously connected to that wall plate in your first photo. It looks like the plate for a Danfoss programmer like we have, but the connections don't look right. On (3) is "HW ON" and I can't see any reason for the jumper between Live and (2). So difficult to guess the functions of the existing wires. You may have to trace them to see where they go and what they do.