Welcome to the forum!!!!!
What a great hobby to start and to work with your daughter with.
Things to consider...
1. what size are you looking into...10+gallons, 55+, or greater. Note most of the time bigger is better when it comes to saltwater. What I mean is that waste accumulates faster in smaller areas so more maintenance is normally involved.
2. Do you have a price limit that you want to stay under. lights, filtration, live rock, and protein skimmers are things that you will need to consider.
3. What kind of fish are you thinking. Clown fish are great (and just a warning, anemones are not for beginners and tank bred clown fish "typically" don't host them. are you thinking corals or not....?
etc...
Myself...I started with a 55 gallon. Its large enough to be enjoyed but not so large as to take up a significant amount of space. 75lbs of live rock and some fish after the cycle.
Lets us know what your thinking and there will be so much help you wont know what to do with it all.