I am new to Android. I have just installed Android Studio and created a default project. Now I am trying to create AVD but am not able to create. Ok button is not enabled. P
The problem is that you havent install the system image, please check the following image
To start the SDK Manager click the icon of SDK manager from Android Studio, like below,
To install this system image, please Open your SDK manager and tick the system image for Android L version ( as you are creating avd for Android L version ), and then install it.
This will load following scree,