This sample app will let you try them out (assuming you have a valid evaluation license - contact support for assistance)
The source code for the sample will let you see how each engine needs to be set up / used.
NOTE: Tesseract3Engine and Tesseract5Engine are royalty free and included with the base OCR addon functionality (licensing required), GlyphReaderEngine and OmniPageEngine have additional licening and royaltys. Contact Sales for more on this.
Simple Atala Console
This is a minimal console app which is mostly designed just to show you the very minimum needed to get Atalasoft running.
This app is an incredibly useful quick starting point for repro issues - Excellent for plonking in your code to provide a working reproduction you can then zip up and send to support.