I need to build the mainscreen with muti choices . The use can enter the number related to the choice and get into it . Can anyone feed me back with some hints to start please .

void  mainscreen()
    cout<< 't\t ---------------------------'<<endl;
    cout<<' \n Course Evaluation'<<endl;
    cout<< 't\t-----------------------------'<<endl;

How much do you know? Do you know how to take user input? Do you know how to use functions?
The switch statement should also proof useful for your case.
Here's a small example that you can modify to your own needs. It's in C, but it gives a nice explanation on how switch/case works