A new publication is created by uploading a single PDF to Publitas. As such, the PDF needs to contain all pages, in the correct order.
If the pages of your publication are stored individually you can ask your designed to provide you with a PDF that binds all pages into a single document. You can also use PDF tools, like Adobe Acrobat or Smallpdf.com to combine the pages into a single document yourself.
Once you have the PDF with all pages included ready, you can upload it to Publitas and create a new online publication.
If you are using the Enterprise version of Publication,