How do I self-enroll myself to a lab account after receiving a code?

Hi

The lab manager sent me a self-enrollment code so that I can self-enroll under the umbrella of the lab account, but I don't know what to do with this code.
I searched about self-enrollment code but couldn't find information about where I have to go to link my account up with the lab account.
Could anybody walk me through how I can link it up?

Thank you.