Redirecting old site to new?

I'm trying to help a client redirect her old website (which she would like to archive and save in case she needs it in the future) to her new website which focuses on her current project. The original site is her full name and so it's the first thing people find when they search her. She has both sites through Squarespace, but a 301 redirect didn't work—I imagine because the two sites have separate domain names? I'm just a copywriter so I'm a little out of my depth here... Does anyone know how I would do this? Do I have to link the domains in some way? Thanks!

The answer will depend on many factors, including who hosts the domain names. If Squarespace hosts the domain names (in addition to the websites), you can simply release the original domain name from the first site and add it to the new one. Squarespace Customer Care can talk you through this. You can reach out to them here for live chat at certain times of the day.