Put arrays inside structs just like any other member. The array becomes part of the struct. Every variable of that type gets its own copy of the entire array. Example: struct Scores { int grades[5]; }; defines a type with an array of 5 integers.
Create Scores s; and access with s.grades[0] through s.grades[4]. The entire array lives inside the struct. If you copy the struct variable, you copy the whole array. This differs from standalone arrays, which decay to pointers.