How can i add text into a category from css drop down menu ?
CSS does not add content. If it adding actual content you are better off hard coding the markup or using PHP ( and a database or CMS) .
However , if all you are adding is stylistic text, such as a count# , or the like you can put a pseudo element at the end or beginning of anyn non-replaced tag.
For example
.category li:after {
content:"this text has been added";}
<ul class='category'>
<li>Item:</li>
<li>Item:</li>
<li>Item:</li>
</ul>
will output:
- Item: this text has been added[]Item: this text has been added[]Item: this text has been added