Updated: Apr 19, 2021
As soon as you decide that you want to learn how to fly, the next big question will be the choice of flight school. Flight schools in the US operate under two distinct set of guidelines which stem from the federal regulations under which it has the authority to train pilots. These are called Part 141 and Part 61. A lot the material on the internet will cover the distinction and some links are below. TLDR; Part 141 is more structured (think school) with a set time and curriculum with regular ground schooling. It is often the best choice for career pilots or if you wish to be on a stricter schedule. Part 61 is more unstructured in a sense that the training is more flexible and the instructor can tailor the course according to student requirements. Within the Pittsburgh region, both kinds of flight schools exist.
The one caveat for Part 141 is that the entry to these flight training programs is often through community colleges. For example Pittsburgh Flight Training Center provides Part 141 training in association with the Community College of Allegheny County (CCAC). Admissions are typically in August.
More details : https://pghflight.com/training/
For Part 61, you may have to spend some time trying to find a Certified Flight Instructor (CFI) who is willing to accept you has a student and can provide access to an airplane. Majority flight schools offer a Part 61, although there might be some wait-times depending on choice of airport and airplane availability. Generally speaking, the longer you are willing to wait or the farther you are willing to travel to get to the airport, the better are your chances of finding a CFI and a plane. Some more resources: