If you are a Group A applicant, grades from summer school courses are submitted to the OUAC by the summer school or the school board. Verify with your summer school that either they or the school board will be sending the grades directly to the OUAC on your behalf.
If this is not the case, you must arrange for an official final transcript to be sent to the OUAC and for photocopies of the transcript to be sent to each of the universities you have applied to, if required. Indicate on the photocopies that the original was sent to the OUAC.
If you are a Group B applicant, contact the summer school to arrange for them to send your official transcript directly to your university choices. Ask your high school to indicate your OUAC Reference Number on your transcript.