How do I insert a number in an arbitrary position, in a position I want?

Hello, how are you? I have this code and I need to know how I can enter a value in an arbitrary position, tried some ways, but I could not. Here is the code:

#ifndef LIST_H
#define LIST_H

template<typename T>
class List {
public:
List() : head(nullptr), tail(nullptr), _size(0) {}

~List() 
{
    auto p = head;

    while (p)
    {
        auto next = p->next;
        delete p;
        p = next;
    }
}

const T& front() const
{
    if (head)
        return head->info;
    else
        throw "Empty list!";
}

const T& back() const
{
    if (tail)
        return tail->info;
    else
        throw "Empty list!";
}

bool empty() const { return head == nullptr; }

unsigned long size() const { return _size; }

void push_front(const T& info)
{
    auto n = new Node(info, head);

    tail = head ? tail : n;
    head = n;
    _size++;
}

void push_back(const T& info)
{
    auto n = new Node(info, nullptr);

    tail ? tail->next = n : head = n; 
    tail = n;
    _size++;
}

void pop_front()
{
    if (!head)
        throw "Lista vazia";

    auto temp = head;
    head = head->next;
    delete temp;

    tail = head ? tail : nullptr;
    _size--;
}

void pop_back()
{
    if (!head)
        throw "Lista vazia";

    auto prev = head;

    while (prev->next and prev->next != tail)
        prev = prev->next;

    delete tail;

    tail == head ? (head = tail = nullptr)
        : (tail = prev, tail->next = nullptr);

    _size--;
}

private:
struct Node {
    T info;
    Node *next;

    Node(const T& i, Node *n) : info(i), next(n) {}
};

Node *head, *tail;
unsigned long _size;
};

#endif