How to read a text file into a struct (C programming)?

I have a text file with a list of first and last names, such as:

Jack Sparrow

Bilbo Baggins

Ramona Flowers

etc.

I also have a struct of arrays defined:

typedef struct {

char firstname [100];

char lastname [100];

} names;

I need to prompt the user to enter the file name (names.txt), which will open the file and read each column in the text file into the 2 arrays above. How would I do that? I've tried mutiple things, but haven't gotten it to work. Also, the text file is just a list of names that I created and will be using so the user won't be entering any names, just the file name.