The linker is what tries to match a function call with a function definition. Most linker errors you will run into is often due to the fact that it can't find the definition. This is mostly because you forgot to include some files, or forgot to link some libraries. Since your error states that it cannot find
sf::Color::Green and
sf::RenderStates::Default, which are from SFML, it's probably because you did not link the SFML library correctly.
As for how to link it correctly, read the
tutorial.
The third linker error (about MSVCRTD.lib) is not SFML related and can be easily
googled