Move the col-12 header part outside of what is now your row and change row to be a flex column. BS4 supports flex and it’s the best way to go for this use case.
Here’s a fiddle
<section class="activities">
<div class="container">
<div class="col-md-12">
<h3 class="text-center text-primary text-uppercase font-weight-bold mb-4">Upcoming activities for october 2019</h3>
</div>
<div class="d-flex justify-content-between">
<div class="col-md-3 mb-sm-5">
<img src="images/img-5.jpg" class="img-fluid">
<span class="d-block text-uppercase font-weight-bold mt-3">October 20</span>
<h4 class="text-uppercase font-weight-bold">Run for charity</h4>
<a href="#" class="btn btn-default btn-primary">More info</a>
</div>
<div class="col-md-3 mb-sm-5">
<img src="images/img-6.jpg" class="img-fluid">
<span class="d-block text-uppercase font-weight-bold mt-3">October 11</span>
<h4 class="text-uppercase font-weight-bold">Book drive</h4>
<a href="#" class="btn btn-default btn-primary">More info</a>
</div>
<div class="col-md-3">
<img src="images/img-7.jpg" class="img-fluid">
<span class="d-block text-uppercase font-weight-bold mt-3">October 21</span>
<h4 class="text-uppercase font-weight-bold">Recycling initiative</h4>
<a href="#" class="btn btn-default btn-primary">More info</a>
</div>
</div>
</div>
</section>
You need to include Bootstrap css.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>General Announcement</title>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css"
integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
</head>
<body>
<section class="activities">
<div class="container">
<div class="row justify-content-between">
<div class="col-md-12">
<h3 class="text-center text-primary text-uppercase font-weight-bold mb-4">Upcoming activities for
october 2019</h3>
</div>
<div class="col-md-3 mb-sm-5">
<img src="images/img-5.jpg" class="img-fluid">
<span class="d-block text-uppercase font-weight-bold mt-3">October 20</span>
<h4 class="text-uppercase font-weight-bold">Run for charity</h4>
<a href="#" class="btn btn-default btn-primary">More info</a>
</div>
<div class="col-md-3 mb-sm-5">
<img src="images/img-6.jpg" class="img-fluid">
<span class="d-block text-uppercase font-weight-bold mt-3">October 11</span>
<h4 class="text-uppercase font-weight-bold">Book drive</h4>
<a href="#" class="btn btn-default btn-primary">More info</a>
</div>
<div class="col-md-3">
<img src="images/img-7.jpg" class="img-fluid">
<span class="d-block text-uppercase font-weight-bold mt-3">October 21</span>
<h4 class="text-uppercase font-weight-bold">Recycling initiative</h4>
<a href="#" class="btn btn-default btn-primary">More info</a>
</div>
</div>
</div>
</section>
</body>
</html>
try this I hope this will work 🙂
How to align these 3 div with more margin?
i tried col-3, but still doesn’t work for me, i want 1 div to be in left, 2nd in center, and 3rd in right. i tried using css for margin, but it’s worse in responsive. do i need to do responsive part to?
Check this image, i want to make this..

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>General Announcement</title>
</head>
<body>
<section class="activities">
<div class="container">
<div class="row">
<div class="col-md-12">
<h3 class="text-center text-primary text-uppercase font-weight-bold mb-4">Upcoming activities for october 2019</h3>
</div>
<div class="col-md-3 mb-sm-5">
<img src="images/img-5.jpg" class="img-fluid">
<span class="d-block text-uppercase font-weight-bold mt-3">October 20</span>
<h4 class="text-uppercase font-weight-bold">Run for charity</h4>
<a href="#" class="btn btn-default btn-primary">More info</a>
</div>
<div class="col-md-3 mb-sm-5">
<img src="images/img-6.jpg" class="img-fluid">
<span class="d-block text-uppercase font-weight-bold mt-3">October 11</span>
<h4 class="text-uppercase font-weight-bold">Book drive</h4>
<a href="#" class="btn btn-default btn-primary">More info</a>
</div>
<div class="col-md-3">
<img src="images/img-7.jpg" class="img-fluid">
<span class="d-block text-uppercase font-weight-bold mt-3">October 21</span>
<h4 class="text-uppercase font-weight-bold">Recycling initiative</h4>
<a href="#" class="btn btn-default btn-primary">More info</a>
</div>
</div>
</div>
</section>
</body>
</html>
Hi, thanks for the help, i am already using bootstrap CDN, i just didn’t posted here..but i found my answer, however thanks for stopping by! 🙂