My "Tool Properties" window fields are:
Title: WinSendKeys
Program: C:\Users\Tyler\Books\Software\Ripping books\WinSendKeys.exe
Working Dir: C:\Users\Tyler\Books\Software\Ripping books\
Parameters: (blank)
-Split_e
That looks alright to me, now add the below stuff into 'Parameters:'
WinSendKeys <50> <"Materials"> <"{RIGHT}">
WinSendKeys [-t 50] [-d] [-w] <"Materials"> <"{RIGHT}">
WinSendKeys [-t 50] [-d] [-w] "Materials" "{RIGHT}"
The window is "Materials Science and Engineering: An Introduction, 8th Edition - CourseSmart Bookshelf". I've tried using the full name and different lengths, different times, different keys... :/
-Split_e
Hm, I've used the default documentation conventions for including optional parameters in square-brackets '[]' and 'explaining words' in angle-brackets '<>', and those shouldn't be actually included in the parameter list.
If you need to use a title with multiple words separated by spaces, then surround that with double-quotes.
So your parameters could be:
"- CourseSmart Bookshelf" {RIGHT}
To select the application CourseSmart Bookshelf with an opened document (the dash before CourseSmart indicates that), and send it a 'cursor right' keystroke, just like you pressed that key on the keyboard. If you want the PgDn key pressed, replace {RIGHT} with {PGDN}. You obviously found the list I referred.

The timedelay should only be changed if your application can't handle the current speed of sending multiple keystrokes. It's only applied if the keystroke names/mnemonics are separated by spaces, so:
"{RIGHT} {RIGHT}" : Sends Right-Cursor, Space, Right-Cursor without any delay
{RIGHT} {RIGHT} : Sends Right-Cursor, (delay for 100 msec), Right-Cursor
You can (and probably should) experiment/test from a cmd-prompt.