This tutorial is more about technique than it is about making a specific centerpiece. Florists take advantage of design mechanics such as floral foam cages and extension rods in order to create a specific look.
The flowers and greenery are more of a personal preference. Take note, however, that mixing different varieties of greens adds a great deal to the unique design while keeping the flowering costs (usually the highest part) at a minimum.
So follow the tutorial keeping in mind that the colors and varieties of greens used are totally designer's choice!
For this design, you'll need: