See the attached graphic (click for larger view). When you first open PLH, it should look like the above image. There should be at least the two default MIC files in the "MIC File" window, you can select the appropriate MIC file in this window. If the window is blank, there must be something wrong with your installation, try reinstalling.

The MIC files live in:

.PLHTextMICNameLists   (where "PLH" is the name of the folder you installed to).

They are text files. They contain a list of channels available for delta injection. I you are not using a DAZ figure, you can create your own list to suit your figure. Apart from seeing the "MIC File" window when you first open PLH, you will be able to access it later, after you press the "Setup Injection Files" or "Setup MorhpPose" button.