In order to install Pegasus on your system, please follow the instructions below:
Go to the following website and see the prerequisites you need to have on your computer before being able to install Pegasus, successfully. http://pegasus.isi.edu/wms/docs/latest/installation.php
Another -recommended- option to get started using Pegasus is to install the VM that has Pegasus pre-installed. http://pegasus.isi.edu/wms/docs/latest/tutorial_vm.php
For MAC you can install Pegasus from the binary tar ball available for MAC from the following downloads page https://pegasus.isi.edu/downloads
Also, you would need to install Condor separately. http://research.cs.wisc.edu/htcondor/downloads/
That has both Pegasus and Condor configured.
Once you have the VM started up in Virtual Box, you can proceed on doing the tutorial.
http://pegasus.isi.edu/wms/docs/latest/tutorial.php That will give you a flavor of using Pegasus and get you running with simple workflows.
This is a simple tutorial that shows how to build and run simple pipelines in the HUB using Pegasus.
Please note that there is no need to run the tutorial on Amazon EC2. It is available in case people want to use Pegasus to run on EC2 Amazon does provide grants / credits for EC2 for educational institutions . But the users need to apply for that http://aws.amazon.com/grants/