Windows 10 for phone Technical preview is out for the Lumia 635 mobile. This blog describes the step by step procedure for installing the windows 10 for phone. Before installing Technical preview make sure the phone is updated to latest Denim update. The windows 10 for phone requires Denim update to be installed.

Once the Denim update is installed install the Windows Insider app http://www.windowsphone.com/en-us/store/app/windows-insider/ed2b1421-6414-4544-bd8d-06d58ee402a5

Sign up on the insider program here https://insider.windows.com/ I signed up using the same live id which I used to login to the Phone.

Once the Windows Insider Program app is installed run the app in the phone.

When you run the App login with the live id.

Select the option you like to get the Update. In my case I selected the Insider Fast option.

Once you select the option the accept the terms

Select the Insider Fast and tap the button at the bottom. This will restart the phone. Then go to settings, Update and check for Update. This will start downloading the update for Windows 10 for phone.

After downloading the update install the update

Install the update. This will install the windows 10 for phone. The install took around 20 minutes.

After you tap done the start screen will appear