No you cannot translate the document yourself. And it just occured to me that you're doing CP, and my earlier response is not entirely applicable - that would only apply to someone processing AOS.
For someone processing CP, I would highly recommend getting the certification notarized (again this is not required for AOS). The translation does not need to be done by a lawyer or a notary, anyone (other than the applicant themselves) highly fluent in both the local and English language can do the translation, as long as they include a signed certification stating they're fluent in both languages and the certification should be notarized. Here's a link to what the certification should look like:
http://www.uscis.gov/forms/forms-and-fees/general-tips-assembling-applications-mailing
http://www.immihelp.com/immigration/document-english-translation.html
For CP, I would highly recommend going with the Affidavit of Translation on the 2nd link above.