Publications page
To manage publications that you own, edit or follow on Medium, go to your publications page, accessible at https://medium.com/me/publications, or by clicking on your user icon in the upper right corner:

Your publications page will look something like this:

Publication Options
New Publication
Click on "New Publication" to create a new publication:

Contributing
Listed at the top under the heading "Contributing To," you will find the publications you own, as well as the ones you contribute to as an editor or writer:

Clicking on a publication to which you're contributing will take you to that publication's home page with any editing options available to your user level.
Following
Listed below are any publications you're currently following in your network. You can unfollow publications by clicking on the "Following" button, which will turn white.

By clicking on "Unsubscribe from Letters" you can turn off receiving letters from publications in your email inbox.
Likewise, if you've unsubscribed, you can click on "Subscribe to Letters" to re-subscribe:

Suggested
Listed below publications you're currently following are new publications suggested for you based on your interests (including tags and authors you follow):

As usual, click on "Follow" to add those publications to your reading list.