FS Genesis - Need Help

OK, I have seen screens of what FS Genesis can do, and now I am very interested. What I want is all of North America - Alaska and Canada included. I see both 38m and 74m meshes. I need both? I know its in various parts, so I will get probably 4 or 5, or however many are needed.
Help would be appreciated
---Stephen
Help would be appreciated

---Stephen