Mantua

We have been mandated to change our website and email domains from our current .org to a .gov I have the domain registered with dotgov.gov and I have cloudflare hosting dns for it. How do I change my website at squarespace to answer to the new domain and the old domain? I have heard we can switch to the new domain and forward queries for the old domain to the new domain...I just don't know how to do that in squarespace.