I am building a website in EE which has menu and menu items . For example, I create a menu called Events which has items called Local Events, International Events etc. The Events, local events, international events are pages which I create using pages module. What I have done is, I created a "Pages" channel. I also created a relationship field from where one can selected the parent page. But the problem is when I when select the drop down it also shows parent+child pages, that is the international, local events pages also in the relation drop down. I just want the main pages to be shown in the relation drop down. Can some suggest a solution, how it can be done. Or should I have to create 2 channel, Main pages channel and sub-pages channel ??
I would recommend you try to stop thinking in terms of 'pages', as you'll only end up frustrated by EE. For your purposes, what you are creating are categorised events, not pages. So set up a single channel - "events", and add an events category group to categorise each one as local or international.
How you list these events on the front end of the site is almost less important than making sure you've tightly defined the content, but there are lots of different ways of doing it. You can then set up a template group called 'events' and pull through the content there, or if you want to override the URL for each event you can use the Pages module to specify a simpler URI.
If you need a short intro section for the listings view(s), you could either hardcode this, or if your client insists on being able to edit it, use Low Variables/global variables. If the intro section is substantial and complex, maybe consider using the Single Entry add-on for a one-off specialised channel.
Above all, avoid using the Structure module. Web content is not pages. Web content is displayed on pages.