Hi Lala, following or being followed isn't a requirement for messaging. You can control messaging in your Privacy settings. Just click on your profile picture, choose Settings, click the Privacy tab and set your Contact Permissions. You can't message people who have their Contact Permissions set to "People I'm following" if they're not following you already. In this case, you should follow them and wait for them to accept your request before you can message them. Hope this helps :)