I need too keep my data primarily itunes library and iphoto library on my HDD
I assume you mean you need to put the music and iphoto library on your external drive. The rules haven't changed since Lion (though iCloud and iTunes Match have added a little twist) so the articles you've found are still accurate.
iTunes:
Open preferences and select the Advanced tab as shown above. Click on Change and select your external hard drive. (You should create a folder on the drive called Music or iTunes first and then select that folder.) Be sure to checkmark Copy files.... As shown in step 2. Then go to the Edit menu and select File>Library>Organize Library You'll get a dialog box - pick the second option. It will take a while for the process to complete.
The downside to this is that now you'll need to have the hard drive connected to use iTunes but you'll have freed up a considerable amount of drive space. If you are interested in iTunes Match (assuming it exists where you live and want to spend the extra money) we can talk about that option. It is what I chose and it lets me keep about 5GB of music on my hard drive at all times while still having access to all 20+GB whenever I have Internet access - which is most of the time.)
iPhoto
Assuming you chose the default setup, keeping your photos in the iPhoto library, just copy the library file which is in your Pictures folder to the external drive. Erase it from your internal drive. Now start up iPhoto while holding the Option button and iPhoto will ask where your library is. If you didn't choose this default option and your photos are scattered in your pictures folder it is more difficult.