There are a lot of ways to incorporate inquiry into a second grade classroom. If you aren't very familar with inquiry, a good place to start is with this article from Science and Children (The Many Levels of Inquiry) that discusses the four types of inquiry. It gives some sample suggestions of how to use the four types of inquiry in your classroom.
From there, I would look my curriculum and decide what types of inquiry I would want to use as I am teaching. What types of topics are you going to be covering in second grade? What information do students need to know in third grade? Knowing that information better helps in planning. If you your state has adopted NGSS and you are unsure, you can always start by looking at the NGSS standards that can be found here.
Another resource you might look at is an ebook, A Year of Inquiry, that the Learning Center has at a nominal fee.
Respond back and we can brainstorm together.