Hello I am a new member to the MODx Community & have a very basic question

First i have read the WIKI regarding installing templates, really I just need to clarify the way templates work.
First I tried to create a template via the admin but found that the ’webdesign’ directory was not automatically created
I then uploaded the new template to assets/templates/webdesign
When I make any modifications via the admin Where are the changes stored if not in the template directory?
if I download webdesign.tpl the changes which I have made in the admin do not affect the template file.
For example I need to be able to modify the template in both dreamweaver & in the admin area.
Sorry if this a stupid newbie question
Once I learn this Framework I hope to be able to contribute & even support others with MODx