Well, just for sure, you'll need to install the program first, before doing anything else, except installing the voices.
So, when you open the program, you'll land in a text window, where you can type any text you want the voice to read. You control the voice's speaking as follows:
Play: press f5
Pause: press f6
Stop: press f7
When you press tab, you can choose, if you want SAPI 4 or SAPI 5 voices, or the voices from Microsoft Speech Platform. When you have chosen a version, you can press tab again, and you'll get a list of the available voices for this SAPI version.
When you've chosen a voice, you can press tab two or three times, and you'll then get to three sliders, which you can change by percent. The first is speed, the second is pitch, and the thirth is volume. When it is as you like, you can press tab again, and you're now back in the text window again, and you can now type your text.
When your text is finished, you can do two things. To save the text as a textfile, you can press ctrl+alt+s, and to save the text as a audiofile, you can press ctrl+w.
Hope this helps.
Best regards: Aksel Christoffersen