Hello,
That page is pretty old and really only provides possible "concepts" of integration.
In time we've created a new one, but there's no step-by-step because... Magento is Magento!
I mean: don't know what your situation is, but Magento is powerful yet supercomplex to properly manage.
Unless you REALLY need it and you PERFECTLY know how it works, it would not be my recommended platform to use.
Now we have an integration code that provides all the basics for RTD/Magento installation. If you're interested in it, please issue a support ticket from your admin panel with subject "Magento plugin request for Alex". It will be $150 for the copy.
That version of the plugin currently offers the following:
Magento admin panel:
- ability to see details of RTD designs when looking order page, with links to thumbnails, order page and revise page
- ability to link product from RTD to Magento
Magento site:
- remove normal "add to cart" buttons for products with RTD links
- added "design online" and "view templates" links for products, with inline popup
- ability to receive RTD orders and add entries into Magento's cart
- ability of having RTD overriding Magento's prices
But before going to ask for it, know the plugin is offered "as is". You might need to tweak some features, and that is meant to be done on your end.
So, my advice would be to face this only if you have strong enough knownledge of both RTD and Magento, as well as a Magento coding abilities.