Not exactly sure as I can't see what you are doing. If you are signed in and seeing this post all you have to do is click the "up arrow" with a circle around it. When you have UPvoted it then the circle will turn blue. There is an arrow right under the bottom of every post and comment. You can only UPvote so many times so if thats the problem just check back and u can UPVote it later. Let me know if you figure it out or not. I will try and help more