If you don't have Visual Studio 2015, go to https://www.visualstudio.com/en-us/downloads/download-visual-studio-vs.aspx and select Visual Studio Community. It is a free version that have all the required capabilities to develop Windows 10 application. You can install the Enterprise Edition if you have the required license. Then launch the installer.
If you already have Visual Studio 2015 installed, in the
Windows Control Panel, go to Program and Features and in the list right click on Microsoft Visual Studi0 2015 (this name can change in function of the installed version of Visual Studio 2015) and select Change.
In the Visual Studio Install dialog, click on
Modify and under Windows and Web Development install all the Universal Windows App Development Tools. It will install, the Windows 10 SDK, a Windows 10 mobile emulator (powered by Hyper-V) and the Visual Studio required to create Windows 10 applications.
When the installation is finished, you can create a new Windows 10 project.
System Requirements: Windows 10
Visual Studio 2015( Universal Windows App Development Tools feature)
Instructions to enable Universal Windows App Development Tools feature during installation during visual studio 2015.
i.During installation one need to select customize and need to check Universal Windows App Development Tools.
ii.If you already have Visual Studio 2015 , you can now add these tools to your existing Visual Studio installation. You can run the installer, or open Programs and Features from Control Panel, select Visual Studio and click Change. Then in setup, click Modify and select the Tools for Universal Windows Apps.
To start with Windows 10 Universal app development you need to have Visual Studio 2015 on a Windows 10 computer. You can buy Windows 10 from here. You can download Visual Studio 2015 from here. You can use Community, Professional or Enterprise versions of Visual Studio. Some features will be limited in the Express version.
You can find a detailed guide how to install Windows 10 here.
When finished you are ready to develop Universal Windows apps!