I am a newbie to expressionengine. I have EE 2.5.5 purchased version. What i want to know is can i create a member registration form and explicitly ask users to register?
The only way to allow members to register without an add-on is to use the Member module's registration functionality. This page is displayed based on your "member" trigger word, uses a completely different set of templates from the rest of your site, and is generally a pain in the ass.
You should see here http://www.sidd3.com/stand-alone-member-registration-form-in-expressionengine/
This weblog having the example code for stand alone member registration form without using any third-party add-on.