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 :

It's texture is this :

And also it has Alpha Texture which came with the model , here it is :

So this island is not supposed to have that little blue square thing , so i deleted that blue place in 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 :).

You should combine these in a paint program, using the alpha texture as the alpha channel of the image, save as PNG. Then use any Transparent shader (Transparent/Diffuse for example)