I am making my website, so how i can start my web design ?
You'll either need to hire someone or learn web design.
Start with HTML and CSS.
If you're referring to the actual design of the interface, determine what your goals are for the site and go from there. Build a mood board with color pallates and fonts, photos or whatever, and come up with a concept and integrate it all in a sketch or a mockup in Adobe PS. Code it like you want it.
If you aren't even at that stage yet, choose a framework and method of building your site that's most appropriate to your level of web-building sophistication and resources you're willing to devote to the technical aspects of your site. You may want to work within a framework or design totally from scratch.
In either case, planning is how you'd start your web design.
It would be helpful if you gave a little bit more information so people can give you better answers. A few initial questions...
What kind of website are you wanting to build?
Have you purchased a domain name or hosting?
Do you want to create the website yourself or hire someone to do it?
You can use tools such as Frontpage or Dreamweaver to edit the site, these tools will give you a lot of help.
To become familiar with the design of your website I think to start with free blogs such http://www.blogger.com