While you can do it directly in the SQL Management Studio, I use it within a database project in Visual Studio 2015
You must install the latest version of
(or you can find the version for VS that you have)
There you will be able to create one from scratch, or import an existing DB. Then you can publish the DB and generate the .bacpac file, you can even publish directly to Azure;)
You can have more information
The good thing ... that you can manage the changes, compare the DB to only upload the changes you have, be able to import or export these changes (bring changes that are in the server), even compare not only the artifact scheme ( tables, procedures, functions, etc.) but also comparison of data.
PS: Take a look if you can to VS2017 have a new way of managing Database projects, with RedGate tools