How do I upload requested documents for my Thai visa application?

I submitted and paid for my DTV for medical reasons in Phnom Penh and got an email *"Other request documents: please upload samples of portfolio/work"*. I can't find where to upload these.

*To upload the above requested documents, please follow the Applicant’s guide as follows:*

*1. Log in to our website at www.thaievisa.go.th.*

*2. Check “Request Document” notification or click “Manage Visa Application” tab.*

I get until here, but can't find the following tabs.

*3. Select “Status Checking” tab and click “View”.*

*4. After clicking on “Reference No.” tab, please upload requested documents and click “Submit”.*

*5. Confirm the attachment of the requested documents by clicking “Accept & Confirm”.*

*6. Your Booking Status will change form “Request Document” to “Pending Document Check”.*

Where do I find these tabs?