Nowhere. Affiliate links (also known as referral links) are not allowed to be in a post anywhere on this forum. You can however have them in your signature.
Just like what Mr. achow101 a staff of the forum. You can't post any affiliate link here in forum for it is prohibited and I guess you need first to read the rules of the forum.
You can found it in here just take time to read so that you are going to be guided :
https://bitcointalk.org/index.php?topic=703657.0And that is the only way to promote your affiliate link with your signature. But for creating a thread or commenting it, that is against the forum law.
It is stated
4. No referral code (ref link) spam.