You could try joining Keelhaulers or Bens creek canoe clubs. Both paddle Slippery Creek and the Youghegeney regularly. Also may be able to get some personal classes from Riversport in Confluence PA. (Yough).
Well, an obvious choice would be the Three Rivers Paddling Club if they are able to hold their Slip Clinic on the Slippery Rock Creek this Spring. It has traditionally been held the first weekend of June but no guarantees for this year given the virus pandemic. They have also traditionally held an event "the Turkey Bash" on the lower Youghiogheny later in the year. Members of the club paddle the Slip and the lower Yough on a regular basis.