How to use query parameters in PowerBI?

I'm fairly new using PowerBI.

I need to create a report using a query like this:

     SELECT something
        FROM mytable
        WHERE 
            (DescMedAcc LIKE @Param1 OR DescErog LIKE @Param1) AND ....

I'm using PowerBI , directQuery then publish report on a PowerBI report server.

Why can't use @Param1 ? What am I wrong ?