Within the software you are able to set the html title through the html module.
Highlights of the title module are:
This module is placed into your design using the following module placement tag:
{module tag='module_title'}
Within the default design that is within the html head between the <title> and </title> tags. If you have changed the design you can still place the above tag where you want the title module content to appear.
You would manage any page by page titles within the following admin tool:
PAGE MODULES > MISC > TITLE MODULE
Within that admin tool you can manage the language specific html titles per page. Click the edit button next to each language on your site to manage the title tag contents used when that language is selected.
To manage the category specific titles you would go to the following admin tool:
CATEGORIES > CATEGORIES > [EDIT] (next to the category you wish to edit)
There are screenshots and additional details on the title module here within the support wiki