In order to progress in GreenSpace you are going to have to know how to craft. Crafting is done at the workshop that you set up from the build menu (see Designing your World).
Materials are the neat things that you find while cleaning trash. Each piece of trash that you clean has a certain type of material that drops once it is cleaned. To check on how many materials you have, click on the icon in the bottom right corner of your screen that looks like an open box. This will open your inventory where you can see your materials, consumables you made from research and the items that you have stored away.
Now that you have your materials you can craft special items that can be used for both crafting more complicated items and for research. To craft all you need to do is to click on your workshop and scroll through until you find the item that you need. Once you have found the item you can see everything that is needed to craft it. If you do not have enough materials to make the item you can either clean garbage that create the materials or you can spend some RocketFuel to buy the supplies you need.
So go on, clean up some trash and see what you find!