experiences while adding rss feeds

It was very frustating while adding rss url feeds, since in class we were not explained exactly how to do it. Since I do not know a lot about it I only ended up going to sites that have the orange rss button. It would be really helpful to have a way to add any website to as an rss feed url. It was very much tiring because there are very few websites that help you do this. Other than that I want to be able to know more so that in the future it is not as frustating.