We use FitDEGREE for scheduling classes. If you already have a FitDEGREE account, you can search for "Triangle Foundry" in the app (or click "Register" below) and start registering for classes.
If you need to create an account, you can do that here. You can also download the FitDEGREE app and search for "Triangle Foundry" to create an account directly on the app.
Membership is not required to take classes. See all the pricing information here.