Login to your account. Usually you would end up in Domain manager, so just go straight to your domain and press Forward button (the one with green arrow) and choose "Forward subdomain".
From there, you can add any CNAME you want.
You might also want to forward your top-level-domain (e.g. example.com) to www subdomain (e.g. www.example.com), and CNAME www.example.com to your pagekite URL (e.g. you.pagekite.me). Otherwise those who enter your top level domain name will end up on GoDaddy default page.
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Step 2: On Goddady: Create CNAME with: Host=www value=domain.you.pagekite.me
Step 4: Run pagekite on your device like:
pagekite.py --clean --insecure --frontend=www.domain.com:80 --service_on=http:www.domain.com:localhost:82:KEY_OF_YOUR_ACCOUNT