Resource URL is incorrect
The alert is incorrect.  As long as you are not having any other issues besides the alert, you can tell the alert not to remind you again.

In addition (now that I see the issue with Contribution pages - sorry I missed that), make sure you have the base page set under CMS settings in the CiviCRM administration settings. 



In WP go to settings, Permalinks. Make sure that they are not set to Plain



Lastly make sure the base page is published.  the page '/civicrm' is added on install