Google Account
You will also need to have a Google sign in. On the top right hand corner of Google page you will see a sign in tab. Follow the simple instructions to get your google sign in. If you have a Gmail email account already, you will be able to sign in using this account.
A link to instructions here if you need it - (https://accounts.google.com/signup)
Google+ Account required
Now if you are very new to Affiliate Marketing and don't have an account already then make it something that you do as a mater of priority as soon as you have your website niche chosen.
A link to Google+ for instructions on setting up a Google+ account is here (https://plus.google.com/)
Google+ can be used to link website articles to as well as other website content. You may like to post your website landing page or your 'posts' page to Google+ to help get exposure and traffic.
If you are linking site pages to Google+ make sure you have SEO set up for the page or it will not rank.
I do recommend sharing it on G+, but keep in mind that it'll only appear so fast in the first page for you. For everyone else it depends on their search and browsing history.