how to add space between pictures

Review the CSS Box Model.  

https://www.w3schools.com/css/css_boxmodel.asp

Depends how you have your images set up.

You could apply a margin directly to the images:

<img src="image_left.jpg" alt="" style="margin-right: 20px;">

<img src="image_right.jpg" alt="" style="margin-left: 20px;">

You could add a class to the images:

<img class="imgLeft" src="image_left.jpg" alt="">

<img class="imgRight" src="image_right.jpg" alt="">

Then use some css selectors:

.imgLeft {

margin-right: 20px;

}

.imgRight {

margin-left: 20px;

}

You could wrap your images in a container:

<div class="images">

<img src="image_left.jpg" alt="">

<img src="image_right.jpg" alt="">

</div>

Then use flex to align them:

images {

display: flex;

justify-content: space-between;

}

If you happen to be using Bootstrap you could use the inbuilt classes:

<img class="mr-2" src="image_left.jpg" alt="">

<img class="ml-2" src="image_right.jpg" alt="">