Step 1: Launch Adobe Illustrator from the desktop
Step 2: Illustrator will ask you to choose a file size. Choose "Letter". (Note that the measurement of "Letter" is points rather than inches or pixels. Points are Illustrator's standard for measurement.)
Step 3: Start with a new project rather than opening a document you might already have. Starting with a new project will avoid issues that commonly occur when file parameters from a previous file don't match Illustrator's parameters (i.e., it will save you time and frustration to start fresh at this point).
Step 4: Note that Illustrator automatically launches the "Essentials" Workspace as its default. From the menu at the top left of the screen, select Window > Workspace > Essentials Classic
Step 5: Take a look at your workspace. You've already discovered the menu at the top. On the left you will see the double tool bar, and on the right are icons that open panels, palettes and tools.
Step 6: Notice that the color space for Illustrator is CMYK, as it is a system designed to create documents optimal for printing. By contrast, Photoshop is RGB which is optimal for digital images.
Step 7: Find the Selection tool in the upper left corner with in the left-side tool bar. You will need this tool often. It is the tool you can use to help you transition from one tool to another tool.
Step 8: Make a rectangle. Use the Selection tool to select the Rectangle tool. Then move the mouse to the middle of the page, click and drag the tool to make a rectangle of any size. Move the rectangle by using the selection tool, clicking on the rectangle, dragging and then releasing.
Step 9: Note that the Rectangle represents a filled object as opposed to lines surrounding an empty space. The interior part of this object is called "the Fill" and the lines are called "the Stroke. Right now, the Fill is white and the Stroke is black. Change the color of the Fill and the Stroke by using the Fill and the Stroke tools from the top part of the Workspace.
Step 10: Change the Properties (e.g., width and height) of the rectangle by using the Properties Palette on the right side of the Workspace. You can also change the size of the rectangle by using the Selection tool. Click on the corner of the rectangle and drag to make it thinner, wider. To maintain the shape, hold the shift key while dragging the rectangle's corner with the Selection tool. 
Step 11: Rotate the rectangle. Move the Selection tool to the outside of the rectangle's corner, which will make the Rotate tool available.
Step 12: Find the additional tools on the left-side toolbar by clicking and holding any one of the desired tools.
Step 13: Find the layers menu on the right side of the Workspace on the right-side tool bar. The Layer Tool allows you to move objects to the foreground or background.
Step 14: Find the Text Tool on the left-side tool bar and explore adding text to your document. The Fill and the Stroke of the text can be changed in the same way that you did for the Rectangle.
Step 15: Save your file. It will automatically save as an Adobe Illustrator file (.ai), which you can reopen and edit again the next time you are using Adobe Illustrator. If you want to open the file on a different platform, go to File > Export >Export As and then select the file type you need (.png is the recommended image filetype). A menu with questions will appear. Click Ok. Save it in a location where you will find it later.
These are the basics for getting started with Adobe Illustrator. For more in-depth information and tutorials, we recommend that you use CWRU's LinkedIn Learning portal: https://www.linkedin.com/learning-login/