You may write either a description or a set of instructions. In either case, the final document should be two to three pages of textual material. You may incorporate graphics as illustrations, but the amount of room they take up must be added to the two to three page minimum of textual material. Descriptive and instructive are definitely not the same kinds of writing. When you tell someone how to do something, each step should start with a verb plus an implied you as its subject.
Instructions are ubiquitous in technical writing.
You can find them in boxes containing things that require assembly, accompanying medications, directing operation of tools and equipment. Many are very poorly written, as you are probably aware. They may not show any concern for introducing the instructions so that readers will want to follow them. They may not feature the imperative mood form for verbs, or they may not provide graphics that do an adequate job of assisting understanding. Look at Markel's chapter 20 if you choose to write instructions.