I am looking to add the ability to show and edit the ID field of one of my database through the data manager in the cms. Can anyone please help me out? Thanks in advanced.
You can show the ID field like any other:
$sfield->addFieldToTab('Root.Main', new ReadonlyField('ID', 'Record ID'));
However, you can't make it editable - the ID is expected to be immutable, and is automatically generated. I can't think if a reason why you would want to make the ID editable - perhaps if you say why you need to do this an alternative solution can be found.
Note: for some databases it would be technically possible to allow editing the ID in the CMS, but this would be a very bad idea.