Postgresql query help

[reddrum]

I am new to Postgresql and am trying to run a simple query.
This string returns an error ” ERROR: relation "tblone" does not exist”.

$sql = "SELECT ID, First, Last, Phone FROM tblOne";

This string works but only with the double quots on the field names.

$sql = 'SELECT "ID", "First", "Last", "Phone" FROM "public"."tblOne"';

I haven’t seen any examples that include the public syntax to find the table
Does anyone know what may be causing this?
Thanks