To access a password protected blog, it is necessary to first receive an invitation from the blog administrator. You will receive an email message requesting you join the blog and a URL to click to accept the invitation. Begin by clicking in the link appearing in the text of the email. If that does not work, copy the URL and paste it into an Internet browser.
Once you reach the URL, you will be asked to login. If you already have a Google account, use your Google username and password to login and you will automatically be connected to the blog (though you may need to click on "View Blog" to see it). If you do not have a Google account, you will see a link inviting you to set-up an account. Follow that link and go through the process of getting your Google account. Once you have the account, you may be automatically connected to the blog (though you may have to click on "View Blog"). If you are not automatically connected, return to your email account and click on the URL in the original email message. Use your new Google account login and password to gain access to the blog.
View the video below for a visual description of the above explanation. Note that this and other training videos are available at TeacherTube (use tag "keeler").