|You should read up on the AND and OR functions in Excel Help. That will help you understand the solution I'm offering below.|
However, while the the solution I'm offering fulfills your requirements, I don't think it's actually what you are looking for.
You've told us what you want if C3 = C and D3 = A or A*, but you haven't told us what you want if those conditions aren't met.
In other words, you have not provided a value_if_false for the IF statement. Therefore, this solution is going to default to FALSE if the conditions aren't met.
This suggestion includes a value_if_false argument: