That's a good start.
Here are a few tips that came to my mind when I visited your home page:
make sure your pages are valid XHTML according to the W3C
Regarding the engligh / nepali date converter, I don't really understand it's use on your home page ... You should move it to a sub page of your site.
Otherwise, I like the layout and colors and your topic is definitely intersting and useful!
Regarding search engines, there would be a lot to tell ... once you'll have a good content, you'll need to optimise the <title> of your pages (btw, you need to make use of <h1></h1> <h2></h2> in your pages to define your titles and subtitles!!), add some meta tags as well (they don't have direct influence on search engine ranking but help in many other ways).
Then you'll need to get links to your site, and links and links and links ...
Take a look at : http://forums.digitalpoint.com/showthread.php?t=224828
Good luck ;-)