In Blender, you can combine two materials into one new material by using the node editor.

Go to the "Materials" tab in the Properties panel and create a new material.

In the node editor, select the first material you want to combine by clicking on its name in the list of materials on the right-hand side.

Add a "Mix Shader" node (Add -> Shader -> Mix Shader) and connect the output of the first material to the top input of the "Mix Shader" node.

Select the second material you want to combine and connect its output to the bottom input of the "Mix Shader" node.

Adjust the "Fac" slider on the "Mix Shader" node to control the blending between the two materials.

Connect the output of the "Mix Shader" node to the "Surface" input of the Material Output node.

Finally, assign the new material to the object by selecting it from the list of materials in the "Materials" tab.

That's it! You have now combined two materials into one new material in Blender.