Settings/[your name]/iCloud/Manage Storage/Change Storage Plan.
This is not a chat service, and is not a way to communicate directly with Apple; it is a user-to-user technical support forum. If you have a question or issue that you think another user can help you with please describe it in as much detail as you can and a user who sees your request and thinks they can help will answer, but that might not be immediate; it could be hours later. Here is some advice on how to do that effectively→Writing an effective Apple Support Communities post.
If you want to contact Apple use the Get Support link at the top of this page or call Apple by choosing a number from this list→Contact Apple for support and service - Apple Support
Here is some guidance on how to get the most out of ASC→Writing an effective Apple Support Communities post