Visit the jetbrains webstorm website and initiate the install.
Visit File - Settings - Languages & Frameworks - TypeScript
Install the TypeScript 1.5 Alpha (or other desired version)
npm install microsoft/typescript
Click the Edit button to change the Compiler version. Browse to the bin folder
Open the TypeScript Compiler Tool Window (View | Tool Windows | TypeScript Compiler), and click the Compile All button on the toolbar.
If you have not opened the TypeScript Compiler Tool Window yet and it is not available from the View menu, choose Help | Find Action, then find and launch the TypeScript Compile All action from the list.