To search for an email in your account, type into the search bar found at the top of your inbox. (Image 1)
You are also able to narrow down your search by using filters. For example, if you wanted to find a specific email from John Doe that was sent with an attachment within a certain time period, click the icon on the right hand side of the search bar . This will bring up options that you are able to fill in and use to find the email.
Image 1