lets go line by line
#include <iostream> // this includes the header file or whatever for iostream and allows you to use the cin and cout functions and other stuff
using namespace std; // this is optional, is the namespace for c++ std library.. I have seen lots of people instead of using this you can prefix your commands with std:: (e.g. "std::cout << string;") but that looks messy and I'm still not sure why they do it so just use "using namespace std;" then you won't have to worry about it
int main() // this is the entry point for a regular c++ program.. no matter what functions come before or after in the source, the main() func will be the first function called when program is executed.. as with any declaration of a function you must specify a return var type (int in this case, void may work too) the name of the function (main in this case, but for other functions any valid identifier can be used) then declare any other variables passed to the function in the parentheses. We're not using that in the main function so we just say "int main()". Once the function is declared, you use the squiggly brackets {} to list statements to be executed in order within the function. All statements must be separated by a semicolon ";". The program should terminate at the end of the main function. (thats what return does)
now for the stuff within the {}:
float deg_f, deg_c;
// this statement declares two floating point (allows any number of decimal places) variables (after re-reading your problem, you may wish to use "double" instead of "float", the difference is size) deg_f and deg_c which are the same as your F and C you could name them that if you wanted to. The important thing is: variable type then identifier, identifier.. semicolon";"
Any valid identifier will suffice I just like the format I used.. your professor might find it a lil strange so either of these lines can be used equivalently: (as long as you call the vars with the same name you give them in the declaration)
float deg_f, deg_c;
double F,C; //either one works.
now since you say you are familiar with c in and out, lets skip to the math bit.. to assign a value to a variable, start a statement like this:
deg_c =
anything after the "=" sign and before a ";" semicolon will be evaluated and assigned to the variable. (numbers are literal constants and get handled just like numbers should)
e.g: "deg_c = (5*(deg_f - 32)/9);"
This statement will, in compliance with order of operations, subtract 32 from deg_f, multiply by 5/9, and assign the value to deg_c, which can then be streamed to cout to display in the window like so:
cout << "Temp in C: " << deg_c << "\n";
Finally once we are all done with the important stuff, its time to close the program.
return 0;
So, this statement will end the main function. It actually does all kinds of cool stuff with error codes with a nonzero argument and shit but that's not important right now. Depending on software stuff I don't understand, your console should but MAY not pause and wait for a key to be pressed to close the window. Some folks may find that they run a program like this and the window immediately closes after execution (not letting them read the results of the program execution) if thats the case for you, we'll need to add a little function to pause, but that really shouldn't be necessary.
So that's pretty much it. Make sure your {} brackets are placed properly, and all statements end with a ";" (the #include statement doesn't need a semicolon, it is a preprocessor directive and is read as the entire line). Remember, with the exception of // comments and "#" preprocessor commands, the compiler ignores things like spaces, new lines, tabs.. Those formatting things are just to make the code aesthetically pleasing and easy to work with. The things that really determine the structure of a program are the control structure brackets {} and semicolons ";" between statements. These will probably be your most common errors at first so look out for lines with no ";"!
As far as how to use your compiler.. I can tell you how to write the code but you're going to have to figure out your software I dunno anything about it. Use your help files. Btw, everything I covered here can also be found in these tutorials:
http://www.cplusplus.com/doc/tutorial/program_structure/
http://www.cplusplus.com/doc/tutorial/variables/
http://www.cplusplus.com/doc/tutorial/operators/
I highly recommend you look through that stuff before posting any more questions. These should be the first things you learn when using C++.