You're not explaining, Aida. You're attempting (unsuccessfully) to translate. Please try to tell us what your proverb means, not what it says.
At the moment it's not making any sense, and here's why (or this is how I understand what you're saying):
If you can (already) reach your goals with (i.e. by using) your feet, how is this possible other than if they already know how to walk? Therefore the idea of teaching them to walk is daft. You would be teaching them something they already know.
Or is that what the proverb is trying to say? It would then be similar to the English saying: Don't try to teach your grandmother how to suck eggs.