You can add an account to a campaign upon creation of the Account. See here for how to create a prospect account.
If you forgot to add the account to a campaign upon account creation, or intend to add the account to a campaign at a later time you can certainly do so!
Begin by selecting the blue icon of an envelope with a plus sign to send the Campaign.
Note: If the icon is green, that means the Snapshot Report has already been sent for this account, regardless of whether that was via a Campaign, or a one off email.
Click Send Campaign Emails to send the prospect four marketing campaign emails over the next few weeks. Leaving this unchecked will allow you to send a single email with a custom message and a link to the Snapshot Report.
Click Send to send the first email. If the Snapshot Report was just created, the report will be sent 24 hours later.
Once the account has been added to a Marketing Automation Campaign, a C icon will appear beside the account name.