Security warning! - Don't share your login information.
It's vital that you are careful when you want to share your website with other collaborators. With your login, someone can remove your ownership, lock you out and it can be very difficult to correct the problem - if at all.
Squarespace have a clever way of collaborating meaning that you can invite an administrator or other level of contributor without compromising your ownership of the website. Here is a 2 minute video showing you how to do it.
(It's also a good idea to make sure you can see that you own the website if someone else started it for you.)
Inviting a Contributor