Simply type your update and when you are ready to link to someone type an @ sign and immediately start typing their name. No spaces!
Ex. @GirlyGirlzBows will link to Girly Girlz Bows @Sara Blair will link to Sara Blair.
Go try it now and see how fun it can be to link to some in your next post. Actually, "Like" Best Thing Since Slice Bread and then give me a shout out in your post and see how it works! ;)