在项目上右键，然后选择Manage NuGet Packages

搜索EntityFramework，然后Install

accept

Attempting to gather dependencies information for package 'EntityFramework.6.1.3' with respect to project 'EFDemo', targeting '.NETFramework,Version=v4.5'
Attempting to resolve dependencies for package 'EntityFramework.6.1.3' with DependencyBehavior 'Lowest'
Resolving actions to install package 'EntityFramework.6.1.3'
Resolved actions to install package 'EntityFramework.6.1.3'
Adding package 'EntityFramework.6.1.3' to folder 'D:\SourceCode\GitHub\EFBasicTutorials\packages'
Added package 'EntityFramework.6.1.3' to folder 'D:\SourceCode\GitHub\EFBasicTutorials\packages'
Added package 'EntityFramework.6.1.3' to 'packages.config'
Executing script file 'D:\SourceCode\GitHub\EFBasicTutorials\packages\EntityFramework.6.1.3\tools\init.ps1'…
Executing script file 'D:\SourceCode\GitHub\EFBasicTutorials\packages\EntityFramework.6.1.3\tools\install.ps1'…

Type 'get-help EntityFramework' to see all available Entity Framework commands.
Successfully installed 'EntityFramework 6.1.3' to EFDemo
========== Finished ==========