lib/Tumblr/API/Client.php
public function follow($blogName)
    {
        $options = array('url' => $this->blogUrl($blogName));

        return $this->postRequest('v2/user/follow', $options, false);
    }
public function follow($blogName)
    {
        $options = array('url' => $this->blogUrl($blogName));

        return $this->postRequest('v2/user/follow', $options, false);
    }
Follow a blog

@param  string $blogName the name of the blog to follow
@return array  the response array