Add a page of any type
- In Office SharePoint Designer 2007, open the site to which you want to add the new page.
- On the File menu, click New.
The New dialog box opens.
- On the Page tab, in the leftmost pane, click the category of page that you want to add.
- In the center pane, click the type of page that you want to add.
- Make any changes that you want under Options.
For example, for ASP.NET pages such as ASPX and
master pages, you can change the programming language that is included
in the page directive.
- Click OK to add the page.
Note For certain page types, there are additional wizards or dialog boxes that you must complete at this point.
A new, unsaved page is added to the current site.
- On the File menu, click Save, or press CTRL+S.
- In the Save As dialog box, type a name for the new page in the File name box, and then click Save.
http://office.microsoft.com/en-us/sharepoint-designer-help/add-a-page-to-a-sharepoint-site-HA010100907.aspx