c++ how to do else if statements

// Program to check whether an integer is positive or negative
// This program considers 0 as a positive number

#include <iostream>
using namespace std;

int main() {
     int number;

    cout << "Enter an integer: ";
    cin >> number;
    if (number >= 0) {
        cout << "You entered a positive integer: " << number << endl;
    }
    else {
        cout << "You entered a negative integer: " << number << endl;
    }
    cout << "This line is always printed.";
    return 0;
}

if (variable) {
  variable is true 
  }

if (condition) {
    // block of code if condition is true
}
else {
    // block of code if condition is false
}

  if (condition1) {
  // block of code to be executed if 
  condition1 is true
} else if (condition2) {
  // block of 
  code to be executed if the condition1 is false and condition2 is true

  } else {
  // block of code to be executed if the condition1 is false 
  and condition2 is false
}