vawt;
First. Make sure "Auto Format" is selected [between the preview and post button below text entry box].
Second. Find the site you want to share, do whatever your system requires to get the URL copied into the clipboard.
Third. at some spot in your post just paste in that http....part. preview the post and it should show as a link with the location as the clickable text.
Its all in that "Auto Format" selection. It recognizes web addresses and makes them links.
Easy as falling off a bar stool.
Cheers.
TomW