What should I do with the robots.txt file in order to have my site found with the search engines?

Robots.txt has nothing to do with your site being found on the search engines. Robots.txt file tells search engines that have already found your website what parts of the site they can index in their database and what search engines are even allowed to access your site to add them to their databases.

You need to add it to a search site or have some website on the internet have a link to it to.