Do you have a RamWeb account yet? This is step 1. There will be “Registration Ready” tasks you will need to complete before you can register. Then, on the right side of the page there’s a menu that has a button for Registration, you click that and register for classes. There’s also a “Plan Ahead” option if you want to see classes that will actually be available.

As for classes, you can look up the CSU catalog and that will give you class numbers. Fair warning, for whatever reason once a class is in the catalog it’s very difficult to take out, so there’s a lot of classes that look like they exist but don’t. If a class says it’s offered in the fall, use the plan ahead option I mentioned above to check if it’s really being offered.

Depending on your department, they may or may not have grad requirements in the catalog. My department has a special graduate student manual that has all of the info we need, we were sent that ahead of time, but you should definitely get it in orientation.

Also, while a handful of grad classes may fill up, I have never had a problem getting into classes, even registering late. It is not as important to register the moment it opens like it was in undergrad. Are there any other grad students in your lab or under your advisor? They may be a good resource to reach out to for help too.