How do i put banners on my profile page?

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Hi! I saw many people with advertising banners on their pages,banners to get referrals on PTC sites and i also would like to put one on my page but i can't for for some reason.So i go to my profile,click edit profile and there's a HTLM box thingy and i copy and paste the htlm of my banner and click on save changes.When i go to view my profile,nothing's there.I tried several times but i just can't get it to work.I wonder what i'm doing wrong.Please help me.