Need a little more detail but there are lots of options - look at feedforall.com or just create a site using wordpress.org software that comes with a feed.
Several different solutions, depends on if you want a static feed, so you could use a desktop based tool to crawl your site and build a feed, or if you want a dynamic one. If you want to go for the second option, you can either use a CMS automatically generating feeds like wordpress or install a script doing this job on your server. Plenty of (free) stuff around, hard to judge what fits your needs.