If you mean in this forum then you click on the link icon (second from the right that looks like a globe and chain), enter the URL, press return and enter the link text then press enter again.
If you mean Tiny URL redirection service you can find that
here If you mean in Apple Mail then select the word you want to attach the link to, press Command+k, enter the URL then press return.
If you mean the HTML code used to create links in a browser there are numerous options and/or variations but the general form is
<a href="http://yoururlgoeshere">the link word or phrase goes here</a>
Rita