My 6 and 1/2 month old baby is constipated after eating solids- is she not ready?

Maybe. Babies' digestive systems do mature at different rates. When babies get constipated on solids, making some adjustments will often solve the problem. And sometimes, just forgoing the solids for a couple of more weeks is in order. Once babies are taking solids, water can be a nice everyday addition, perhaps around 2 ounces twice a day, to keep things soft and moving.
Probably. There is no hurry, but food selection will impact stool frequency.Rice cereal, bananas and applesauce are likely to slow things down.Barley cereal, prune or apple juice speeds things up. Some times it just takes a while for you to figure out your kids system.