Question How to overwrite one tex on another like photoshop layer?

I m trying to overlay one texture on another,i try to use blend node and set to overwrite,it works.but I want to overwrite a transparency texture on another ,how to do that?

please look at the picture, the second picture has alpha channel,how can i only overwrite the ice-cream on background?

 

Plugging the Alpha output from your second Sample Texture node into the Opacity input of the Blend node should do the trick.
The Opacity output acts like a mask from Photoshop, so you can use the alpha of your texture here to define which part should show your icecream and which should show the other texture.

 

it works my friend, thank you very much!