There are a number of ways to install Open edX. The method you use depends on your needs and your skills.
Many people choose to have a service provider install and manage Open edX for them. This is a good option if you do not have a technical staff to handle the complexity of an Open edX installation. We have a community-maintained list of Open edX service providers. They will be glad to help you.
A few service providers offer self-service installation methods that might be perfect for your needs:
If you would rather manage an Open edX installation yourself, the Open edX wiki has a page that will help you find the installation method that is right for your needs. The Open Operations wiki home page has more information.