Ok well it sounds like you definitely need some help, one big problem is this can easily become a case of topping from the bottom. That's where the sub effectively directs play and the dom goes along with it which of course isn't really Ds at all.
To assist it would really help if you laid out some more information about yourselves and what you both like, what kinks you are into, if you enjoy pain, bondage, humiliation, etc, etc.
Often in the past I have helped couples by designing activities, things like short tasks, longer scenes and and complete weekends. These are kind of a script for getting you started with plenty of room to improvise as you go. By sticking to the roles in the script you get to play the parts of Dom and sub and get used to it, hopefully after a while it starts to become more natural and you can simply play your own games any time you like.
If this is something that interests you message me for more details but feel free to continue discussion here also.