Personal Account: this is the URL https://pinterest.com/ you can use to have direct access to sign up with Pinterest. Here you can see the interface.
I recommend you sign up using the “your email address” link because that will give you the ability to decide your username right away. You will be able to edit that username at any time in your profile area.
Business Account: and this is the URL http://business.pinterest.com/ you can use to have direct access to sign up with Pinterest as a business.
Click on “Join as a Business”
For this one you will have the chance to pick a username as well. You don’t need to search for a hot keyword for this because what you really want is that people may find you by the name of your company.
Don’t forget to go to your e-mail and confirm your Pinterest account. Now you are done with Step 2.