Does anyone know how do blend layers, not using Multiply, Mixture ect. Like, blending them with out showing the edges of the pictures?

Ermm... what do you mean by "blend?" (Please give a well-defined mathematical function if at all possible )

As for not showing edges, I know how to do that in the Gimp, if I understand what you mean.

Thanks, but I got it. I forgot it was called masking. Here's an example that I made.