By default, the slider will display the 4 most recent posts you've published.
01 How to edit the slider
To edit the fonts and colors of the slider, go to Theme > Customize > Advanced > click on "Links" to expand the dropdown > scroll down until you find the Slider section.
You can easily show/hide the content, post date, snippet, etc, on the slider. Go to Layout > open the Slider widget > edit the settings (number of posts, show/hide the post content, date, etc).
Here's the code for the slider, in case the widget is deleted (add it to a HTML/JavaScript widget in Layout):
<script type="text/javascript">
var numposts = 4;
var random_posts = !1;
var showpostcontent = true;
var showpostdate = false;
var showpostsummary = false;
var numchars = 1;
var displaymore = false;
var buttontext = "read more";
var showarrows = true;
var showdots = false;
</script>
<script type="text/javascript" src="/feeds/posts/default/?published&alt=json-in-script&callback=postslider"></script>02 How to display posts from a label
Go to your blog dashboard > Layout > open the Slider widget > replace this:
<script type="text/javascript" src="/feeds/posts/default/?published&alt=json-in-script&callback=postslider"></script>With this:
<script type="text/javascript" src="/feeds/posts/default/-/Label Name?published&alt=json-in-script&callback=postslider"></script>Replace Label Name with the name of the label you want to display posts from.
Important: Blogger's labels are case sensistive, so the label has to be written exactly the same way you've written it in your posts, otherwise no posts will be displayed.