Hi guys I really need some help with one C program. I don't really know where to start from so I'll be happy to all of your advices

I'm a beginner at C and I know all the stuff but my teacher decided to give us one task which is "pretty easy" according to him but all we've studied so far is if-else and those kind of stuff. So this is it:
In the text file C:\data\myfile.txt there are some integer numbers separated with one or more spaces. Write:
1) function: for copying the file int myCpy( FILE *); in a file with name given from the user (which is opened in the function) , and replacing all the spaces with tabs.
2) function void midl( FILE *); for displaying the average of the numbers higher than 10 and lesser than 20.
3) function main() , which opens the file, calls the two funtions and closes the file.
Thanks to all the repies in advance

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