in this sample, how can i center the element p and an image element ?
First, since you appear to be using Bootstrap syntax, you need to add either Bootstrap 4 (the most recent version) or Bootstrap 3 to your Codepen CSS settings.
Before you start centering text, you need to read more about Bootstrap’s Grid System to layout your page. Then, you can learn more about alignment to position text, images, etc… within your layout.
Like @RandellDawson, suggested, you need to learn about Bootstrap so you know how to build things with it. For example, columns must add up to 12 in Bootstrap 3, but you only had six in there.
I recommend this tutorial:
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