If your gross freelancing income exceeds $3,500, CRA requires you to report this as "Self-Employed Income" and you will be liable to make CPP Contributions on any net amount that exceeds this $3,500 threshold. 

CRA requires you to complete a T2125 - Statement of Business Activities, and you can claim your freelancing income on this form as well as any related expenses. While you may not have a Business Name or Address, you can use your own name and address for this information.

Here's a tip from TurboTax you may find helpful: Run a Business Out of Your Home: What You Can Claim?