I need to have a page, called "Seminars", that contains only list of seminars and their short descriptions.
Under this page I need to have pages with full description for every seminar.
Should I use a "blog module" to create section like this?
If the blog module is fine, please explain how to define a separate "BlogEntry.ss" and "BlogHolder.ss" because I also have specific blogs on my website and I changed templates "BlogEntry.ss" and "BlogHolder.ss".
Create two different Page types: SeminarHolder and SeminarPage.
The SeminarPage is your detail page. Create all the needed fields there.
The SeminarHolder contains several seminar pages and displays its children summarized. Here's how your site-structure would look like: