I have just tested Ads 1.6.0 and posted unregistered an ad with attachment and pictures.
Do you have an older version and if so what is?

Sorin

You should update to the latest version (1.6.0) as in 1.5.9 some attachment issues were fixed among other issues.
Use this form to ask for an update:
http://www.thefactory.ro/contact-us/product-update-request.html
and read the upgrade info in this thread:
http://www.thefactory.ro/joomla-forum/ads-factory/ads-factory-1-5-x-1-6-x-update-script-3003.msg18215.html.html#msg18215

If upgrade is not possible ( lot of customizations made in the core files) you can still ask for the latest version and compare the controllers and models differences using tools as WinMerge.

Sorin

Hi again,

If you mean  permitting word files / only word files
you have the com_adsman/config.php

setting:

define("ads_allowed_attachments", 'doc,txt,zip,rar' );

As you can see by default there already is  "doc" file in the allowed extensions list.
You can remove or add other extensions to fit your needs.

Cheers,
Sorin