How can I get the C compiler for VisSim and TI F28035?

Is the C compiler provided by Visual Solutions or do I need to get the compiler separately?

TI makes the C compiler

You can learn how to download Code Composer here. You can choose between a full version for a fee and a free version that is only limited by the codesize. The codesize limit of 64K is quite large given the efficiency of the VisSim code generator.