Text Clips are added/edited/removed from the Text Clips Window, you can bring this up by doing View | Windows | Text Clips. You'll see something like this:
Clip Window Screenshot
The drop-down box at the top lets you select the scheme you want to view, in your case that will be C++. Then you will see a list of available clips. Shortcuts for clips (e.g. your ifs) are a new feature in 2.1.4, and not all schemes have updated clips for this yet - including C++. This means that while you see a list of clips, they don't have shortcuts yet. You can double-click on any clip to insert it, this was the limit of the old functionality.
To create a new clip, click on the Plus sign at the bottom of the text clips window, this will bring up the clip editor window where you can assign a user-friendly name, a shortcut, and the text for the clip. Once you've added the clip, the shortcut you specified should be instantly available in all C++ files.
You can also edit all the pre-canned clips to add shortcuts that work for you.
Much of this was in the help link I pointed you to at the top, I have now clarified this page further:
http://pnotepad.org/docs/text_clips
As a developer working on Free software in my spare time, I have to balance time spent on developing features, time spent on documentation and support, time spent on planning and learning, and finally the time I spend on the "real life" that I'm supposed to have. I'm trying to improve the documentation, screencasts, and other ideas more but it all has to fit into the small time I have left for working on side projects.
Open source projects like Programmer's Notepad have to rely not only on the developer but also on the community to help with user education. Hence forums and free-to-edit wikis that everyone can contribute to.