首先欢迎您进入Xamarin世界.

First off welcome to the Xamarin world.

第二，您所拥有的模板是正确的.他们只是在Visual Studio 2017中进行了一些改动.例如，如果要创建PCL(可移植类库)项目，请选择跨平台应用程序，然后单击确定".比您得到以下屏幕:

Secondly your templates that you have are correct. They simply changed up a bit in visual studio 2017. For instance, if you want to create a PCL ( Portable Class Library ) project, you select cross-platform app and click ok. Than you get following screen:

这里可以选择您的编码策略(我在屏幕截图中选择了PCL).

Here can select your coding strategy ( I chose PCL in screenshot ).

如果有更多的问题不要犹豫，问好运；)

If more questions don't hesistate to ask and goodluck ;)