How did you sign him up? Did you sign up for an online school or something? And who is supposed to be emailing you? I'd be very wary of dealing with a school district via email.
Most homeschoolers must actually purchase materials that are physically shipped to your home. I get mine mostly from www.christianbook.com but there are tons of other places out there as well. I also use the free worksheets from this website and EdHelper as well as many others.
It all depends on what type of curriculum you would like to teach your grandson. If you want it to incorporate the Christian faith there are plenty of curriculum you can choose from. My children learn from different curriculum, Social Studies is not from the same company as Math and ect. I did find a website that you can join for free and there is all different kinds of curriculum on there. All you have to do is post one book, DVD, or CD of your choice (it explains it on the website) and you can order from other homeschoolers all you have to do is pay the shipping and the book or whatever is yours. That's where I got all my children's books this year and I wish I knew about it sooner.