Those don't look like standard AVR names. Typically the avr header files use singly defined names for peripheral registers, so for instance USART 0 Control Register A will be named UCSR0A, Control Register B will be UCSR0B, etc. Unlike some other platforms, they don't tend to define structs for peripherals. The exception, IIRC, are the XMega parts, which I believe do have structs defined.
Atmel Studio is really good at just working (except when it doesn't), so make sure to use the new project wizard and properly select your part. That should include the right header files. Then consult the header files or some example code to figure out the proper register names. Once you know the scheme it's pretty easy to figure out the names you want.