Adding a custom page to DotShoppingCart is as simple as adding a page to any ASP.NET website. You can just create a page in folder that you like and start customizing your own content. If you wish to add a custom page that is integrated with DotShoppingCart e.g. page editor, theme etc, you will need to follow these steps.
1) Decide where you want to put the new page and create an entry in table DSC_Block_Type_lkp . And then retrieve the blockTypeId for the entry that has just been created.
e.g INSERT INTO DSC_Block_Type_lkp (Type, VirtualPath) VALUES ('My Page', '/Controls/Core/MyPage.ascx')
2) Add an entry to web\module.config to wire up the page url.
<add name="root" value="">
<pages>
<clear />
<add name="MyPage" blockTypeId="99" />
</pages>
</add>
3) Create a usercontrol under the path that you decided in step 1 e.g. web\controls\core\MyPage.ascx and make sure it's derived from PageBlockUserControl . You can take a look at any existing pages e.g. web\controls\UnSubscribe.ascx.cs for reference.