how to call class in css code example

Example 1: css class

.myclass {
  border:1px solid black;
  background-color: #d2d2d2;
  height:20px;
  width:60px;
}
/*If you give this class to a div in html, it will get the styles you gave
to that class. You can add multiple classes to a div, and multiple divs
can get that class. */
/* I hope I helped! */

Example 2: css class attribute

<h1 class="Class">Content</h1>
<h1 id="id">Content</h1>
Css: 
.class
#id

Example 3: css calss

.ThisIsAClassName{
  font-family: sans-serif;
}