S.H.
Although, your daughter is old enough for juice, drinking it isn't recommended. I've done quite a bit of reading on this, and it can be difficult for a baby to process. Juice has no nutritional value and can cause stomach cramps & diarrhea. To be sure, I asked my pediatrician about this, and he agreed that there is no reason to be giving my 8 mo old son juice.
As far as knowing what foods and how much to feed your daughter, Gerber has a great resource on their website that allows your to download weekly menus based on your child's age and developmental stage. It's an easy way to plan a well-balanced diet. They do all the work for you...even providing a shopping list of items included in the menu.