How do I let users be able to view, update and delete their own content?
You can use Views. Create a view of content on your site and use table format, list the fields as listed in admin/content. Add a relationship to the content:author so as to get access to the user table. In contextual filters (arguments for drupal 6), add user:uid => provide default value => user id from logged in user. Add a page display to your view and optionally provide a normal menu entry (or do that with the menu system) and Save your view. Go to the page you created, you should see only the content you created. To be able to mass delete or perform other bulk operations on the content, use Views Bulk Operations