I have a question how to post stuff in our profile?

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I've went to other peoples profiles and I see that they put up banners for ptc sites or other sites of interest to them. I was trying to figure out how to do that. Can we do that? Will we get in trouble. I know you shouldn't post referral links on the actual post. But I have a couple of banners I want to put up in my profile. If someone could help me I would be really grateful. Have a great day!