So this is a very early version of the gathering, but basically, you'll be able to find these resources scattered throughout the Free Roam areas. Once found and grabbed, they will "magically" be added to your inventory.
We've had discussions about a "gathering bag/pouch" where you dump the items in. But for this first pass, we want to make it easy and simple to gather.
Just stock up until you have enough of the resources you need to start crafting or repairing something. More on crafting and repairing in the near future.