the answer all your queries depends on the website that you want...is it a personal website or a company website?

first of all you would need a "space" to put your site in...there are a lot of companies that provide domains for this purpose...and it's quite cheap (50USD per year)...as for the designs...you can do it your self or there are some that provide free templates that you could use.

all of this can be done by you or you could hire someone to do it...again it depends on what you want for the site

here is a link that could be some help to you:
http://www.websitedesignbasics.com/