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. Please help.
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,
You don't have system images installed for Android (L) Preview. Use this link to setup or use the Android SDK manager for downloading the Android-L system images.
Change target for your AVD see try target which matches your application. see points in link.
Make sure the permissions on the SDK folder are set correctly. You will need write permission.
来源：https://stackoverflow.com/questions/25738692/not-able-to-create-avd-in-android-studio