In the AE effect control window for that layer, there should be a drop-down selector to choose the layer you want.
For evolution property press the Alt/Option key and click the stopwatch in the Effects Control Panel for the evolution property then type in your expression.
For Set Matte you need two layers. As Dave said you find the Use For Matte option and select the layer you wish to use.
The last is just a blend mode or a track matte of a masked solid...
Thank you Dave and Rick!
You should thank Todd too. His suggestion is an invaluable one. You need a solid foundation in AE or your work in it will just be full of frustration.
Sometimes frustration drives one forward !
HAve yo never heard the expression, "Practice Makes Perfect" ?
Have yo never heard the expression, "Practice Makes Perfect" ?
Sure -- but AE isn't the kind of application amenable to learning by doing. It's a labyrinth.
Now, you can go through the labyrinth and try to keep all the dead ends straight -- good luck with that! -- or you can take advantage of instructions that help you navigate through it.
Which sounds better to you?