Highlight the text that you want to turn into a link, then click the little globe button (next to the mail icon towards the mid-right) above your post, paste the link URL in the little box that pops up, and voila.
Highlight the text that you want to turn into a link, then click the little globe button (next to the mail icon towards the mid-right) above your post, paste the link URL in the little box that pops up, and voila.