How to get variable from help of variable_get function, function has saved value on any db table or some where else?
To get the value use:
$valueVar = variable_get('myvar');
It is saved on a generic database table called [prefix]_variable, if you are not using prefix, the name of the table is variable. Look at: https://www.drupal.org/forum/support/module-development-and-code-questions/2009-05-14/help-which-table-is-the-variable
You can use variable_set() to set the value and that will store it in the database. e.g.
Then to retreive it:
$myvar = variable_get('myvar');
You could create a page with a form to allow CMS users to change the values of your variables. See this for examples: https://api.drupal.org/api/drupal/modules%21system%21system.module/function/system_settings_form/7.x