*Please copy the whole script, not only the part mentioned here!*
Then create a new bookmark, give it a name like "share2Friendica" and paste the script in the address field. Save it. Now you can click on that bookmarklet every time you want to share a website, you are currently reading. A new small window will open where title is prefilled and the website you want to share is put as attachement in the body of the new post.