i want to simply filter a document by its description .... how can i do that ?

You can use Ctrl+F and search by value in the column with description.

Hi .. thanks for your answer ... but now I'm trying to make more complex filter ... now i have a document and a number of users can write and edit on it ... but i want to filter that document in a way to display only the records that this user wrote ... and the other users records will be invisible ... if you can help in this case I'll be so thankful

You can set filters on Filters tab of Dynamic list to make it static, make this programmatically to change dynamically, or include this filter into View or even Read settings of role to make this unchangeable and be applied in all lists where this document is displayed.