how to get a canadian security clearance?

I understand that the basic level Reliability Status (RS) clearance requires five years in Canada, a job agency may be able to help you.

Four levels of personnel screening exist - all shown in bold below

Reliability Status (RS) - formerly known as enhanced reliability status (ERS)
Reliability checks are done by verifying personal data, criminal records check, educational, and professional qualifications, data on previous employment and references.
As well, a fingerprint check, and a credit check may be required.
This level of clearance will grant the right to access designated documents with markings of Protected A, B & C information/assets on a need-to-know basis.
It is mandatory for individuals when the duties or tasks of a position or contract necessitate access to protected information and assets, regardless of the duration of an assignment.

Security assessment/clearances
Individuals who require access to more sensitive information (or access to sensitive federal government sites and/or assets) because of their job will be required to sign the Security Clearance Form (TBS/SCT 330-60e).

There are three basic levels of clearance:

Confidential (Level 1)
In addition to the RS checks, foreign employments, immediate relatives, and marriages/common-law relationships must be declared and be screened.
This level of clearance will grant the right to access designated and classified information up to Confidential level on a need-to-know basis. Department Heads have the discretion to allow for an individual to access Secret level information without higher level clearance on a case-to-case basis.

Secret (Level 2)
Same as Confidential.
This level of clearance will grant the right to access designated and classified information up to Secret level on a need-to-know basis. Department Heads have the discretion to allow for an individual to access Top Secret-level information without higher-level clearance on a case-to-case basis.

Top Secret (Level 3)
In addition to the checks at the Secret level, foreign travels, assets, and character references must be given. Field check will also be conducted prior to granting the clearance.
This level of clearance will grant the right to access all designated and classified information on a need-to-know basis.