I used a plugin called WP Import to import a mass amount of users to my website. I now want to be able for them to log in using those accounts. How am I able to send them their passwords or get them to login to their account that we created for them?
You shouldn't have to send them passwords. That's a bad idea.
Instead, make sure your web server has email setup properly and your user accounts have the correct email addresses. Then all you'll have to do is send them the link to the
Forgot Password link provided by WordPress by default. It looks like this:
Then from that page they'll be able to reset their passwords using their own email address.
Whichever method you follow, you must make sure your web server can send email to your users properly.
Read more about WordPress password reset options.
You should give them a one-use limited-life access key via email this key is embedded in a URL (and it can only be used once, so if they try using it again, it is disabled, and if it not used within a short period of time, say an hour, it is disabled and a new key must be sent). Then, when the user clicks on that URL, he/she is redirected to the reset password page, where they enter a new password for their account.