No matter what page you are on within the site, there's a big, blue search bar at the very top. Here you can enter in information about individuals that you're looking for. Simply type in the information and click "Find". If you are looking for specific individuals type in their first or last name (case sensitive) and select "First Name" or "Last Name" from the drop down box to the right. Select "Find" and scope the results. (Or if you are just looking to invite other people who have the same first or last name as you do, this is a good method to use as well.)
Maybe you can't quite remember the name of someone you worked with, but you know what company they worked for. Or, perhaps, you want to see who of your colleagues from a specific Company are on the network. No problem! Simply type the name of the company in the blue search bar, select "Company" from the drop down box and click "Find." You can also enter any of this information on the "My Home" page under "Search Network."
Your search results will yield all individuals who meet the search criteria. Their names will show up in blue and if you want to view their profile page click their name. Now you can browse their profile and even endorse them. But don't forget to invite them to your network!