Mark, click the "chain"

Mark, here is the interface. If you click on the picture and look closely you can see a little box in yellow that says link. The chain is right above it. It goes font (drop down), size (drop down), bold (icon b), italic (icon i), text color (icon t), and then the chain. You should see the chain mark. If you click the "chain" a box will come up. Then you just type the link in. Trying clicking the "chain," Mark.