Cannot send emails from Outbox in Outlook Office for Mac 2011

I can receive emails but cannot send them. The Outbox shows up occasionally with all of the emails I have written today in it.  Once I go to the inbox it disappears and I can't access it (find it anywhere).  Have tired "send all" did not work. I followed an instruction to change the authentication to "use incoming server info" no luck, and the Outbox disappeared again.  I moved a test email from outbox to drafts and sent it, did not work.  Computer was off for over a week as I was on a trip and used my iPad for email.  I have never had this problem before and cannot find anything on Microsoft Help that will help.  I need to send these emails and to be able to send others. Cannot get technical support. Please HELP!!