First, make sure that you have changed your settings in

Preferences Main »» Meta Tags and Footer
http://yoursite.com/modules/system/admin.php?fct=preferences&op=show&confcat_id=3

META ROBOTS = index,follow

and also META DESCRIPTION and KEYWORDS and RATING.

You should not need to do anything with the robots.txt file, so make sure you have not given the wrong info here!

this is the usual list thats required.

User-agent: *
Disallow: /cgi-bin/
Disallow: /tmp/
Disallow: /cache/
Disallow: /class/
Disallow: /images/
Disallow: /include/
Disallow: /install/
Disallow: /kernel/
Disallow: /language/
Disallow: /templates_c/
Disallow: /themes/
Disallow: /uploads/

Now ... you have to sit back and wait .....

Google can be a long time coming, I mean months sometimes.

To get you a head start, post your url and site on forums like this, it gets crawled very often and your link along with it.

Search engines like sites with relevant content. That means keeping as much page content in line with your titles as possible and as many titles in line with your categories as possible and as many categories in line with your site title, meta description, keywords as possible. If you can get a domain with your main keyword in it even better.

Get the picture? good relevant content, lots of repeated keywords, high in the page but not overdone. (keyword stuffing) Yes, it's an art!

There's a whole box of advice on SE Optimisation and you will do well to check out other sources for better details.

Good luck, stay cool