It's different when talking about learning a musical instrument. The key of learning an instrument is:..............Practice. While for other subjects, e.g. languages, which they could learn it thru other means e.g. multimedia programs. To encourage more practices, one needs motivation. Certainly at small age, motivation from parents are definitely a "bonus". Practice a lot really needs one to have more endurance, encouragements, recognition. It's really long road to learn an instrument. For languages, they could just listen more and speak it more everyday. For sports, they could play it with other children.
I guess you will have to try to learn at least how to read the sheet music by yourself first (you should be able to learn it online), it's no harm and really not that difficult. You probably cannot help her with the fingering unless you also learn piano yourself. But frankly, probably parents like us is a bit too old now..... (may be you are younger!)
My wife also know have zero music sense too but she attend JMC with my daughter and she has also started piano lesson recently (we are just as late but Tom Lee is more stricter on age). So far the progress is quite good as the piano teacher keep telling us she is pushing faster (we only startd 1.5 months ago). I guess my wife learn a bit basic from JMC so she can still manage to help our daughter. I never learn piano too but have grade 2 violin (hehe, almost 30 yrs ago) and played in a rock band during high school so at least reading and listening is ok. I guess nowadays we as parents are learning again with our kids!