If your instructor has assigned Autodesk products for you to use for your class, the best place to start is on the Autodesk Education Getting Started as a Student Page. That page will walk you through creating your Autodesk account, which may involve submitting additional documentation to prove your eligibility. It also has a video of the process if you find that helpful.
Once your account is created, you can use the instructions on the Autodesk Education Installation Page to download and install the product.
Please note this process will be required to use AutoCAD in IT Services computer labs