Alpha textures?

Hello guys, i need help about importing alpha textures. I have a model and it seems like this with it's normal texture :

http://ressim.net/s/upload/57c08388.png

It's texture is this :

http://www.upload.gen.tr/resim.php/www/0zi1mcdn/dunya.jpg.html

And also it has Alpha Texture which came with the model , here it is : http://ressim.net/s/upload/ce5c6fe1.jpg

So this island is not supposed to have that little blue square thing , so i deleted that blue place in Paint.net and made it transparant, and i imported it with the shader Unlit>TransparantCutout ,and that blue places were lost as I wanted. But it's not being affected by any lights,the support guy from 3d model site says me that i need to import the normal texture and alpha one, but i just don't know how to import alpha i mean which shader should i use, please help me out :).