How to add Variables in Drupal (and how to visualize them)? I'm new to Drupal Answers, but I've been programming for a few years now.

I'm looking to create something simple (at least I think) within the Drupal CMS to use throughout the site. I want to create a variable, let's call it $phonenumber and store the value of this variable, like (789) 456-7894 (not a real number). That way I may use the value of this variable on my site without hardcoding the number.

I have installed the Variable module, which has little to no documentation, and poor usability all around. 

I build in PHP, I know this is basic, Drupal is built on PHP. But for some reason I cannot get a printr or echo of the variable on any page to work.
Are you aware of the devel module? It is typically used in dev versions of a site only, and is not recommended for production status sites.

After you enable that module, you'll get many features, such as dprint_r(), dpm() (I like the last one for debugging). For more details, refer to https://www.drupal.org/node/174575 ...