If you have created any Profiles in the past, they'll be listed alphabetically on this page. If you haven't done one yet, your page will, of course, start off blank.
The next page that opens is where you fill out the details of the Vendor you're building the Profile for and any info about the current project they may be working on with you.
Next, you'll set how many days you allow your vendors to get in a response. Remember, once they've been "invited" to their Profile, their access never ends. They can get in as often as they like and proactively maintain their info for you.
The third step is choosing whether or not you want to start with a blank Profile, or use prior, saved examples that are applicable to this Vendor. To finish, simply click on Create Your Profile.
Now your Vendor Profile is in a draft mode. The final steps are to go in and approve any sections in your profile, then add Contacts from your list of Vendor Contacts, and finally Publish your Profile, which sends them an invitation. These are obviously very important steps otherwise your Vendors won't have any other way to respond.
Please see Section #5 on Publishing a Vendor Profile for the how-to's.