Hi, I've never studied coding or developing, so I'm having a bit of trouble figuring this out. Basically what I want my formula text to do is, if the Days Since Last Update field > 90 AND if Stage Name does not equal Closed Won or Closed Lost, show an image of a red exclamation point so that users know this opportunity needs to be reviewed. 

Here is the formula I am using: IF(AND(Days_Since_Last_Update__c > 90), IMAGE ("/servlet/servlet.FileDownload?file=015j0000000PsCZ","Red:High Importance"),null) 

The only issue is, I'm not sure how to insert the piece about if the Stage Name (which is a picklist) equals Closed Won / Closed Lost, the red image does not have to be shown and the opportunity does not have to be reviewed. 

Thank you so much for your help!!