By A Web Design
For making settings in the global configuration for Joomla1.7, you have to first login through the administrative panel of joomla by simply entering the url_of_your_website/administrator in your browser.
Enter the username, password and leave the Language to Default, click on Login as shown in Diagram 1.

Diagram 1
After logging in to the backend, a control panel page opens as shown in Diagram 2.
The Control Panel provides access to many default Joomla! functions and features. From the Control Panel, you can create and manage articles and categories. Other features available in the Control Panel are the media, menu, language, and user managers.

Diagram 2
The Global Configuration screen allows you to configure Joomla with various personal settings so that Joomla behaves exactly as you want it to.
Access Joomla’s global configuration settings from the control panel or from Site -> Global Configuration as shown in Diagram 3.

Diagram 3
There are four tabs: Site, System, Server and Permissions.
The Site settings are related to the Main Site, Metadata, SEO and Cookie Settings.
The System settings are related to System, Debug, Cache and Session settings.
The Server settings are related to Server, FTP, Database and Mail settings.
The Permissions setting is used to set global permissions for user groups.
The various new options provided in Joomla 1.7 are as shown in Diagram 4. The rest of the options are same as Joomla1.5.
The Site Settings have a new field for setting the default access level for new users.
The Metadata Settings have a new field for setting content rights. Joomla will add your data to the meta declaration rights within the HTML code.
In SEO settings, there are two new options that can be used:
Unicode Aliases: This lets us to choose between transliteration and unicode aliases. Transliteration is set by default.
Include Site Name in Page Titles: This option if set to ‘Yes’, will begin all Page Titles with the Site name (for example, My Site Name - My Article Name).
Cookie settings are a wonderful feature for evaluating a cookie on different sub domains. You will need this feature if you have a site (eg: site.com) and one or more sub domains (eg: blog.site.com) and you want to offer your users the service to login on site.com and post on blog.site.com. Without this feature, the user would have to login again to post something on blog.site.com.

Diagram 4
User and Media settings are no longer in available in the Global Configuration area in Joomla1.7 as shown in Diagram 5. You will now find User and Media settings in the Options settings of User and Media Manager respectively.
The cache settings are different because the underlying cache system was rewritten and now provides more possibilities. In general, a cache makes your sites faster by storing parts of the HTML in files. The web server can deliver these files extremely fast. It is possible to cache pages, component views and modules. You can purge and clear the cache in Site ? Maintenance.

Diagram 5
All the server settings of Joomla1.7 as shown in Diagram 6 are the same as in Joomla 1.5.

Diagram 6
Joomla 1.7 Global configuration is provided with new Permissions setting, the place to set your global permissions for your user groups as shown in Diagram 7.
Before making any changes do read the NOTE at the bottom of the permission settings page. It contains the following message:
1.If you change the setting, it will apply to this and all child groups, components and content.
Please Note that:
Inherited: means that the permissions from the parent group will be used.
Denied: means that no matter what the parent group's setting is, the group being edited cannot take this action.
Allowed: means that the group being edited will be able to take this action (but if this is in conflict with the parent group it will have no impact; a conflict will be indicated by Not Allowed (Locked) under Calculated Settings).
Not Set: is used only for the Public group in global configuration. The Public group is the parent of all other groups. If a permission is not set, it is treated as deny but can be changed for child groups, components, categories and items.
2. If you select a new setting, click Save to refresh the calculated settings.

Diagram 7
You can refer the common features of Joomla1.5 and Joomla1.7 more in details. Please refer to tutorial – Global Configuration of Joomla1.5 .