If you are using an iPad, touch the plus shaped sign in the upper right hand corner and select the search Skype directory option. Type in your contact. Once you do that, click on them and touch the add contact button in the upper right hand corner. Hope this helps!!!
Posted from Apple iPad
Wow, thanks guys! That's been bugging me for ages!
A little more detailed How-To:
- On the current call screen (iPad & iPhone/iPod), hit the little options button next to the other call buttons (it is a circle with 3 horiontal lines inside it), then hit show messages.
- From there, type: /add username -where username is replaced with their skype name.