The easiest way to perform a search is to simply enter a word in the search box and click the search button.  The maximum length of a query cannot exceed 1024 characters.  By default, SharePoint search is case in-sensitive, which means you can type in upper case, lower case or a mix and still get the same search results.
 
You can enter a multiple words into the search box.  When more than one word is entered into the search box, SharePoint uses the AND query.  The AND query simply ensures that only results containing all the words entered are returned.  This is not the same as entering a phrase into the search box.
Phrases are entered into the search box by enclosing the words in quotation marks.  For example:  “Employee Handbook” would be wrapped with quotes if you want SharePoint to treat it as a phrase.  When SharePoint search treats a query as a phrase, it only returns results containing the exact match, in the exact order, as you entered it.
 
You can also tell the search engine to exclude results with specific words in them by entering a minus sign (-) in front of the word or phrase you want to exclude.  For example:  Employee –Handbook would return results relevant to the word “Employee”, but not if the result also contained the word “Handbook” within its content.  

Another powerful option available to you is the use of properties (or meta-data).  Property based queries simply follow the format of <property name>:<value>.  For example, if you wanted to find all documents authored by Sean Bordner, you could make use of the “Author” property and enter Author:Sean Bordner into the search box and hit search.  

You can even combine these capabilities into a single search.  Let’s say you knew a guy’s name started with S and he authored an employee document, but it wasn’t the Employee Handbook, it was something else… You can’t remember exactly what it was called, or where it was located, but you need to find it.  No problem!  You can enter Employee –Handbook Author:S and let the SharePoint search engine find it for you!


 
Note:  Be sure the Search Core Results web part is not set to permit noise word queries.