You can learn Microsoft SQL Server from various sources. It could be offline resources like books, online resources, paid training, etc. To get started referring to free resources will be a good choice. Once you are good with the basics, enroll in paid training to help you grasp the concepts from scratch to an advanced level that will eventually help you bag better opportunities.
If you aspire to master SQL Server, check out this SQL Course from Intellipaat. This course has helped many professionals to learn and bag exciting job offers. I will also drop a video of a customer who has shared her learning experience with Intellipaat. I hope this video will help you gain better insights.