When listing your event, you can include many outbound links to whatever websites you like. These might include the artist's site, the venue's site, the promoter's site, Facebook, YouTube links, Soundcloud links, Twitter...whatever you like.
The place they don't go is in the event text description. That section doesn't support outbound links, so use the URL section just above the event text description in Eventfinda Pro for that information. Non-linking text URLs are frustrating for people and they're likely to be stripped out by our moderators as they don't link from the text area.