Just head over http://www.xml-sitemaps.com/ to create your sitemap in many dialects for different tastes of various search engines.
Site map? Site maps are easy lol google accepts a plain text file with links you want it to index on separate lines what could be simpler
site maps are generally easy to do but it depends on the nature of the site. If it is static then it is very easy and there are plenty of free tools that will do it for you. If it is a dynamic site, particularly with user created pages then it is a tiny bit more complicated as you realistically have to create a script to dynamically generate the sitemap
Im fimiliar with the Google one but at the same time how many site can you upload through this? and everytime you ad a page you have to sento the site map"
Most you do not need to upload them... you include a link to it in your Robot.txt file and spiders will automatically pick it up. Yes, you should update it each time a page is added or removed hence why it is more complicated on sites where users are able to add pages
Thanks " I have question how about those sites that define the site map in the url!as a page extend" I mean like this site will Google see this as a site map and will it help Google find relevant content regarding your web pages online??? is this good seo tactic?