i want to learn all the things i need to build a website.what all the things i need to learn to build a website ,design it and install plugins like word press?
if you haven't a programming knowladge (html, php...) I recomended You to use word press. you can design a create web site from wordpress. you can download free word press themes from http://themes.wordpress.net/
view my freemori.com site ,have lot of site script,template and website build tools. you can find any you want.
I'd start with somewhere like www.w3schools.com , www.pageresource.com , www.davesite.com , then just practice - trial and error is the best way to learn.
There's not much you need to know about installing plugins in wordpress. Just FTP the plugin and enable it in the wordpress admin. No html or php is needed. You can install new templates the same way. If you want to learn about wordpress this would be a good place to start - "codex.wordpress.org/Main_Page" (Wordpress Docs)