But you don't want to find all those other messages; you just want the ones from Ben. To narrow down your search, you can use keywords. The keyword from:, for example, lets you find messages from a specific person (just as if you were sorting messages in your old mail system).
To begin, type from: in the Gmail search bar. As you type, Gmail opens a list of matching keywords. Select 'from:' from the list or just keep typing. Next, begin typing the person's email address or name. If it's someone you've emailed in the past, Gmail lists matching addresses (so you don't have to type the whole thing). Otherwise, just keep typing the entire name or email address. You don't have to capitalize the name but can enter upper- or lowercase letters.
Tip: To find all messages you sent, including drafts, enter 'from:me' in the search field. You can also view the messages you've sent but not deleted in the Sent Mail label and all drafts in the Drafts label.