So the real goal here is to learn how to perform these tasks without Hazel. Which leads to another question: What is your programming experience?
This includes things like Excel macros, because some of the basic skills are fundamental. For example, the ability to logically thing through cause/effect relationships (X happens, and Y is the consequence), as well as the ability to logically break tasks down into smaller subtasks.
For example, consider your description:
... look through my downloads folder and everything that is over a month old in the downloads folder it takes and puts into the trash, ...
Breaking this down into subtasks:
A. Confine the subtasks to the downloads folder.
B. Find everything over a month old.
C. Move the things found to the trash.
You can do subtasks A & B using a single step in an Automator workflow.
1. Open Automator and choose New Workflow.
2. At left, under Library, select "Files & Folders".
3. In adjacent column, drag the "Find Finder Items" action to the gray workflow area.
4. From the action's "Search" pulldown, choose Downloads.
At this point you have subtask A: results are confined to the downloads folder.
5. From the list of things to find, choose "Date last modified".
6. From the popup next to it, choose "is not in the last".
7. Enter 30 into the box.
8. Choose days from the last popup.
At this point, you've added subtask B: find things over 30 days old.
The next subtask (C) is to move the found items to the trash. On the left, look for the "Move Finder Items to Trash" action. Drag it below the "Find Finder Items" in the workflow.
Boom. Done.
Well, not really done, because you have to test it. And you might want to change it, such as using "Date last opened" instead of "Date last modified". But the basic logic is complete.
I suggest going through an actual tutorial on Automator, so you know the fundamentals of how it works, and how actions can (or can't) be connected.
Be prepared to make several different workflows that have no direct interest for you. These are exercises, and any skill requires exercises before you can effectively undertake the thing you want. No one climbs into a jet airplane and flies it. It takes learning the fundamentals and lots of boring practice first.