I receive money for translation services that I did and entered it in Other income. How do I do to claim expenses due to this service rendered. I'm not a business yet.

If you wish to claim expenses to offset the income you received, you need to complete the T2125 - Statement of Business Activities to do so. Although you are not officially a business yet, this is the correct way to report your income & expenses. If the Gross Income (prior to expenses) you received exceeds $3,500, CRA requires you to report it this way as you may be liable to make "CPP Contributions for the Self-Employed".

You can complete the form using minimal entries are; the business name can be your name and the business address can be your home address.

https://turbotax.intuit.ca/tips/what-is-a-business-for-tax-purposes-6180