The next step is to create a “back of a napkin” business perspective of your solution. What are the key components and functions? Perhaps a shopping cart, an inventory management thingie, a brain to pull it all together, and a payment processing element. Use whatever media you’re most comfortable to quickly sketch a business architectural cartoon. Show how things are linked.
Allocate all elements from your list at this stage.
The disciplined part of you may be tempted to think about decomposition using proper architectural perspectives (static, dynamic, and physical views). You may be thinking about the meaning of links between boxes. This will come later, but you’re still at a very creative stage. Keep on moving.
Next, create components that would implement / support the business elements and sketch them in the context of your existing operating environment. Again, draw loose associations between existing systems and your components. Now go one level down and decompose each of the components into sub elements (if appropriate).
In my most recent exercise I used a standard sheet of paper cut in half as my work space. As I created sheets I numbered them in sequence of creation. This allows you to spread them on a table (or tape to a white board) without the fear of forgetting your chain of thinking and decisions.
Put the resulting stack of sheets away for a few days.
Now you have enough material to create a discussion document. Use your favorite diagramming tool to create a presentation that’s targeting proper audience. Be sure to remove highly technical material out of the presentation targeting non-technical stakeholders.