You can share the site by doing the following:

1. Go to the sharepoint site.
2. Click the gear icon in the top right corner and select “Site permissions”
3. Click “Add members” and “select Share site only”
4. Type in the email address of the people you’d like to share it with, set the permission level, and a message if you’d like. I suggest keeping the “Send email” option check so they receive a link to the site automatically

When they receive the email, it should take them to a login page. Have them enter the email address you shared the site to. They will be asked for a verification code which will be sent to that email address. Have them accept the terms and they will be able to access the site. By default, this only lasts for 180 days.