How to search Google?

While searching for download links, I always wanted a way where I could limit the search so it doesn't include one of the many downloading services and includes all the rest. As I didn't know a way to tell google NOT to return the results including links that use say, "abc" download service, I used to put the name of the services that I did want google to return in the results. For e.g. if I want to download "Visual Studio 2008" I would request google to search [Visual Studio 2008 xyz], xyz being the service I want to download from. The problem was I don't know all such download services, I don't like downloading from abc for one reason or the other, but including xyz in the query would result in a limited set of pages, while the pages with other services would probably not be returned. I was at a big disadvantage here because there may be a possibility that xyz doesn't provide you to download Visual Studio 2008.

This is just one of the problem, if you are required to do extensive searches you may face a lot of such problems.

I always thought there should be a way, but unfortunately, stupid as I am, I never tried to look for one.

Then in my Text Mining class, the teacher asked us "Does anyone know what is the structure of a query when you want to search say, for "Algorithms" and "Operating Systems" with exactly two words in between". The class remained silent as a response. Then he asked another question "How many of you have read 'How to search google'?". I don't remember the exact name of the document he said but the next day I searched for a document and landed myself on the site:
Google Guide

This is an extensive site with good articles. Each article tells you about so many stuff that at least I didn't know about before. And reading just one article leads you to so many other links (mostly on the same site).
But the guide is very easy to read and understand.
I hope by the time I finish it I know the answer to the query "What do you write when you want to search for 'Algorithms' and 'Operating Systems' with exactly two words in between."