Telling the family!

No matter what age it must be a little nerv racking. 
I'm 21 and me and my partner said we was going to start trying in the new year. I already have a 3 year old. And have found out I'm pregnant sooner than we thought it would happen but still over the moon just nervous about telling my dad.. I want to tell him like a happy tell him rather than just say I'm pregnant anyone have any ideas? 
We're telling him this evening!