First, you need to install Eclipse first by following this site:

http://developer.apple.com/tools/eclipse.html

Second, you need to install Android SDK from this link:

http://developer.android.com/sdk/installing.html

Third, you need to install ADT (Andoid Drevelopment Tools) from this link:

http://developer.android.com/sdk/eclipse-adt.html

Finally, go to SDK directory installation from Terminal. Then goto tools directory and run below “android update sdk”

aoddy$ pwd
/Users/aoddy/android-sdk-mac_86/tools
aoddy$ android update sdk

If you don’t run this command, you cannot see a list of SDK tarket.