How far have you got and where are you stuck?
Do you know how to determine if a number is prime? (if you don't, then you have no chance of writing a program to do it)
As a starting point you could create a program to input a number then display all the even numbers up less than or equal to that number. Then focus on the prime test, when that's done your program will be complete.
A mistake beginners often make is to assume they have to write the whole program in one go. Experts don't do that; they write programs a step at a time - often very small steps; I always start with a simple "hello world" program and make sure it builds without errors and runs, before continuing with the next bit. It's amazing how often people complain they're stuck and post the whole code, which can be in some instances over 600 lines long - I can't believe someone would write that much code without even trying to compile it.