Make sure you are using the correct SSH keys/usernames on both your GitHub account and your local machine. Here’s how you can
do that on GitHub
Also, you might consider using an alternative Git manager. I’ve never heard of Aptana, but I do know that GitHub has an awesome GUI program for managing your repositories.
In the future, this is all much easier and more streamlined on Linux/Unix operating systems like Ubuntu. Ubuntu is geared towards developers and has things like Git and SSH installed correctly by default.