I'm guessing you mean making a sentence/word into a hyperlink for your signature?
If so, type what you want to be clickable and highlight it.
Then click on this symbol:
![](https://i.gyazo.com/5eda0e9e57fd149d09e098d29f21f07a.png)
Paste the link of whatever you want in the box that appears. That should make your sentence/word clickable.