Worth having a good read of the Forum Rules as it’s all set out quite clearly in there what is and isn’t allowed - only fans link would break the no personal contact information rule and no links to pornography.
For general advice about adding links to your post you can simply copy and paste the link, or alternatively click the two rings (next to italics symbol) to add a link within text (like I did above with the forum rules). I’m pretty sure the discobot tutorial covers it too or you can practice these types of things in The Sandbox (and people are usually around to help out if you’re having difficulties!) 