Lessons and courses at Stepik can be created by any registered user.
For that, register and use Create lesson and Create course buttons. When you create a course, you have to choose a plan https://welcome.stepik.org/en/pricing
We do not make agreements with individual instructors. It is enough to agree with Terms of Service during registration. However, if you are a representative of an educational company and you need official agreement, please contact us at firstname.lastname@example.org.