XF 1.3 Google: Adding a Sitemap and a robots.txt file

Right now, I'm trying to get Google to index my website. Apparently, you need a Sitemap and a robots.txt file. I've read the "Google Webmaster Guidelines," however, I'm not sure how to create either file, nor am I sure how to implement both files.

Does anyone know any good suggestions/guides/websites for creating both a sitemap and a robots.txt, as well as implementing them into the Xenforo Website.

Just a word of caution: I'm a beginner to Xenforo, so if you do decide to suggestion something, please spell it out very simply.

Thank you for all of the help. Have a great day :)
And locate file robots.txt at public_html. You try to access it via link yourdomain.com/robots.txt, if you can read the content inside then google can.