Ok, so do you remember how to get user input? You need to do that for part A. The function needs to return the number the user entered so it would have an int as a return type and take no parameters. Inside that function you need to print out a prompt asking for the number of milliseconds. Then you need to read what they type into a variable and return it.
Try writing a function that did that does that, you'll need to use cin and cout here.