Oh my word!!
I am not an expert, but adopted mum to three. Your child has been pulled out of the only world she knows, put in a strange house with strange people and then when she gets upset you have been told to ignore her. Give me strength and a big dose of reality for social workers.
You should do exactly what you think you should do, which is be very (very) calm and soothing and gentle, and if she will let you, hold her and soothe her, and then hold her and soothe her some more. She will be absolutely terrified with no logical understanding of where she is or what is happening. I get so cross with social workers giving bad advice. No matter how much you know she is in the right place and want to give her love and a forever home, she can't understand that the lovely people who took her to the park last week whilst she happily lived with her foster carers have now taken her away from everything safe she has ever known. No wonder she is scared, wouldn't you be?!
Prepare yourself for months/years of her being unsettled. The only advice I can give is do what you think is right. The post about sitting on knee is good, but even that may be too much so try to hold her hand and stroke it and work from there.
Get a visual timetable if too young to understand, and put on pictures of food, bath, story, lullaby song, bedtime and keep to it religiously. Above all else let her know what is going to happen every day at bedtime until it becomes not scary. And then do the same with the rest of the time. Keep repeating calm soothing sounds, just like a mum with a new born baby would.
Sorry for long post. Not really an expert, but have wonderful hindsight (which is what all adopters gain!).