How to use the "set texture parameter value" block in blueprint?

I want to change the texture during the runtime, However, I do not know how to set the texture parameter in the “set texture parameter value” block, I do not know where I can set the texture parameter. can I set it in material?

http://docs.unrealengine.com/latest/images/Engine/Rendering/Materials/MaterialInstances/ConstructionScriptForMID.jpg

youve got most of it covered. Just open your material in the material editor, and for each one of the values you want to change, right click the value in the material editor and select convert to parameter. Then, in the details of the parameter you just created, make sure the name matches your values in the node network above.