Can you still get a sewn in weave?

I want to get my hair done my weave will be sewn into my braid but the girl who is doing it told me to wash my hair because it wass greasy and not to blow dry it so that it can be sort of nappy andso she can grip it better,and im black and i had a perm 2 weeks ago and its still staight and not nappy,her phone is off so i cant contact her,i was thinking white people get sewn in too and their hair doesnt have to be nappy,and i didnt wear a scarf and it feels a little frizzy do you think she can still do it,because i really want it done and dont want to pay extra at a salon,also she did my sisters hair and it was cute so i know she knows what she is doin