If your certification body raised negative audit findings (nonconformities) you have first to correct those nonconformities, remove what is wrong. Then, you have to search the root cause behind each nonconformity. After identifying each root cause, you can implement corrective actions, actions to remove the root causes. Normally, certification bodies specify the time frame for answering to them with a description of the correction and of the corrective action.
The following material will provide you information about answering to audit findings: