I’m confused too. Last time I checked, Squarespace is a website building platform, not really a hosting service. If you host your website with Squarespace, you build your website with Squarespace tools, not WordPress. You can’t host WordPress with Squarespace as far as I know.
If, as others have suggested, you purchased a domain at Squarespace to use here, that makes a lot more sense. But then you’re not redirecting your website to Squarespace, you’re pointing your Squarespace domain to your website with us.
And while that may come across as pedantic, it helps to remember what should go to where so you can better understand what needs to be done where.
Can you please tell us what you have done so far and where you are getting stuck?
Also, did you read this article already?