Converting to Drupal

I am new to Drupal.I have done with the installation of drupal.But now i m not getting the below given problem :
Basically after installing Drupal what are the steps or processes necessary to integrate to a php site. For that i want a more detail information.

Hello all,
I understand this topic was discussed a lot, but I'd like to now what you think of this idea.
I need to redirect a lot of old URLs to the new URLs using 301 redirect.
Here is the idea's implementation:
Create redirect.php page and set it to be default error page for 404 error (page not found) using drupal settings.
the content of the page is as following:

I've installed Drupal (well, really I installed CivicSpace) into the root of my webspace because it will become the main website once I've converted all the old static HTML pages.

I need the HTML pages to continue to be active for a while until I'm ready to flip the switch. I've set my .htaccess to DirectoryIndex index.htm index.php which allows the old pages to be served up first. I can access my CivicSpace installation by typing in the URL www.mydomain.com/index.php.

Can Drupal integrated to the currently running php sites.If Yes what are the steps required to be done for that.What will be the code for configuring drupal with existing php sites.

Has anyone here had to port over a system from the Absolute News Manager System by Xigla Software?

The company I work for is looking for an alternative to this template-based commercial system. In order for me to convince them that it's a good system, I need to show them that their news articles and posts can be ported over without much fuss or degredation in information integrity.

Any help on this would be appreciated.

On a related note, does anyone have or know a well-rounded ad management module for drupal?

Has anyone been successfully integrating phpAdsNew & Drupal?
Please I need help integrating phpAdsNew & Drupal