My step daughter is 18 mts old, her biological father does not see or speak to her(through his own choice). My wife and I are considering that I adopt faith(stepdaughter). However as neither of us have ever done this before it would be useful to know where to start. So if anyone knows how to start the process it would be extremely helpful

First-you need his agreement
Second-you have to terminate his parental rights in court.

Not technically. If they have one signature (say the mother of the child's) they can somehow overwrite his name. I was told this during the adoption court my boyfriend and his ex and the adoptee parents who want my bf's child. But I think this may only be possible if the father (in your case) does not show up for court proceedings concerning the child in question. Though do not quote me on this one. Otherwise you should just be able to acquire guardianship, custody and adoption papers from a lawyer I think. Yet again I am still new to family court so you should double check this information in case I am wrong. So do not quote me on it. But it is what I have heard

You start by contacting a Family Attorney. They will advise you of the process. It generally involves getting the bio father to relinquish his rights and then petitioning the court to adopt.

No court is going to grant adoption without the relinquishment of rights or, at least, a good faith effort to get it. If the bio parent can't be found or contacted, then the court MIGHT grant the adoption. But if the parent is known, then their relinquishment of rights must be obtained.