How can i trace the number of hits to each page and average time spent on that page

You cannot track hits with JavaScript alone. You need to use PHP, ASP or Perl which has the ability to write to a text file or database. Your server must support one of the languages mentioned to be able to use these.

You could get a free hit counter and place it on your site. There are tones of sites out there ofering free hit counters. Try: fxweb.com.

I don't know how you would calculate the average time someone has spent at your site.

I recommend using hitbox.com
They offer an excellent service for free that will tell you all you asked for and much more.

I would recommend http://www.sitemeter.com it's an excellent tracking system for all your pages and you only need a button on your index page and it will track all your pages. Very detailed log records such as time spent on your site, page views, and many more.. Best of all it's free and password protected so nobody can view your stats.

Hope this helps.

Try MyComputer.com three options, free with ads, free with paid per click ads, and £$ for the invisible service plus numerous types of downloadable reports.

It's very good.