Redirect 301 when changing top domain

Site URL: https://www.widala.se

Hello, I am about to change our top domain from .se to .com and use .com/se for Swedish and .com/en for English, ie making a subdirectory. Those changes seems ok (so far, before launching :)) but when I am preparing for the switch I am preparing all redirections for this. The problem is that redirections starts with “/“ and doesn’t contain the top domain. So my question is how I should do this so that the redirections work?   For example I would like www.widala.se redirect to widala.com/se but I don’t know how to do it. Should I write the whole URLs for all redirections? Like this? “Http...dala.se-> http....dala.com/se 301”. 
We have an external web hotel (miss hosting), should I do some or all redirections there instead of in Squarespace?