I wanted to ask,how to add presentation file to asermons without using Docman,I am using joomla 1.7 and you have to pay for Docman,anyway to have it free?

I guess docman is not free, is it? If you wanted to you could just connect directly to the file. Just use a server record and folder to lead to the folder on your site where the PPT is located, then use the PPT name as the file name. Users will then be prompted to open or save the file in PowerPoint.

Alternatively, you could put your powerpoints in SlideShare or similar site then link to them.