To start with Microsoft Azure and cloud services, you need an active Azure subscription and an Azure tenant, which will be obtained with the subscription. There are different ways to order such an subscription.

The following list provides a few options: 

• Microsoft MSDN subscription
• Microsoft Azure free trial 
• Microsoft Azure pass 
• Microsoft Enterprise Agreement (EA) with Azure commitment 
• Microsoft Azure cloud solution provider 
• Microsoft Azure in open licensing 
• Microsoft BizSpark program