When I try to download Facebook it says since the app is over 150mb that it will only download over WiFi. I have a data plan and no WiFi AT ALL so I would like to know how to over ride this setting or whatever I need to do

In addition to the suggestions made by Johnathan Burger, here are other locations where you will find public wi-fi generally:

McDonald’s

Panera Bread

Dunkin Donuts

Buffalo Wild Wings

Marriott Hotels

Whole Foods

Staples

Office Depot

Target

Barnes & Nobel

Best Buy

Public library

Airports

Gyms and yoga studios

Trains & buses

Public parks

Hospitals

Museums

Visit the facebook web site using Safari. You can not bypass the requirement for WiFi when downloading large apps from the app store.

You don't.

Go find a Starbucks, Apple store or friends house with WiFi.

You can't override it. The limitation is an agreement between most US carriers and Apple to protect their networks from saturation.