The default reviewer will be the workflow owner.
Click on the pencil to change the default reviewer or add more reviewers. You can add as many reviewers as you like. Once one of them acts on the request, it is considered done.
Tip: The email address is saved if it has turned grey. If it doesn't turn grey automatically hit Enter or Return on your keyboard after each email entry.
Once you have added all your reviewers, click Update.
To add Conditional approval reviewers inside a Step, click the + button "Add New Conditional approval.
Change Step 1 (Default) name, if desired.
Enter the conditional approval criteria and Reviewer(s) email address(es). You can add multiple Conditional approvals & Reviewers for each approval step.
If conditions are met the reviewer(s) specified for this condition will receive a "Request for approval" email to act on the request.
As soon as one of them acts on it (approves it, declines it, puts it on hold, or sends it back to the requester), the request is closed to the others.
If conditions are not met the request for approval email will be sent to the default reviewer(s).
Our blog post here: http://goo.gl/UUh67f explains the process in details
Click on Back to Step list to close the window and return to the Approval steps list
Repeat to add as many approval steps and reviewers as you need.