The search you created will search for jobs that have all of the words in the "keywords" field anywhere in the job posting. In the e-mail, each search lists all of the jobs that it found that met the search criteria that you specified. If you are receiving irrelevant matches, you will need to modify your criteria. Try typing in more keywords that better represent your experience (try typing in your desired job title or specific skills as keywords).
To edit your search, click on the My Searches tab and login if you have not yet done so. Click on the Edit link next to the search you wish to modify. Then just make the changes to the fields you want and hit the Save Changes button.