How can I link a referral link to a code

Question

<a></a>

Answer 1

just like any other link.

(if you intend to publish it on sololearn, make sure you if this is ok with the terms of use.)

Answer 2

Using anchor tag, or <a> tag, you can use its attribute href="#LINK" replacing #LINK by the link you want to redirect to.
Remember to insert text into the anchor tag too! It wont work instead :)

If you refer to publish a code in sololearn, just press the public button when saving it, but have in mind that you must follow sololearn's the terms of use (don't use other's codes without including credits, etc etc).