how to install monodevelop?,how to open monodevelop?

i create a new c# script and I try to open it.but it says that I didn’t " install monodevelop correctly for example GTK# " how can I escape from this problem and open my script to create my game please answer me now
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Well did you try reinstalling Unity. If that didn’t work install monodevelop from their website. These are some pretty easy things you should have done before posting this question.