Citation information in Google Scholar is gathered from articles in Google Scholar's database and from Google Patents (citations from Google Patents can be elimintated).

1. Go to Google Scholar.
2. Enter some search terms (author name and/or part of the title).  If you want to make your search very narrow, click on the down arrow next to the search box to do an advanced search.  
3. Click on the search button.
4. All results in the list will have a Cited by link at the bottom of the record. Click this link to view who has cited this item. For more information about searching see Google Scholar's Help pages.

To find all of the materials and citation counts for a single researcher, do a name search and click on the name of the researcher for one of his or her articles. This will bring up a list of everything in Google Scholar written by that researcher. To the right, you'll also see a citation index over time and citation counts according to other indices. Depending on if the researcher has set up a profile, the researcher's name might not be clickable; in that case, you can find articles written by that researcher in the list and manually add citation counts.

To be alerted every time articles by a certain researcher are published or cited, click on the Follow button at the top of the screen and enter your email address.