Report Builder - Paginated Report - Parameter with...

Hi,
I need to set up a parameter. I've been following the instructions in this article, but it doesn't cover parameters.
In Report Builder, I have connected to the data source which is a dataset in a Power BI Service workspace.
In Desktop I built a table visual then copied the DAX from performance analyser.
In Report Builder, I created a dataset using the copied DAX.

The issue is I cannot get a Parameter set up in Report Builder.
I have created the parameter p_Shift under Parameters and chosen the relevant field 'Site'[Site Code] from the dataset.
In the dataset under the Parameters tab, I have added the created parameter.
I know the the third step is to go back to the query tab and add a clause to match the field to the paramter. In SQL this would be WHERE 'Site'[Site Code] = (@p_Shift) .
But I can't find information to say what it sould be in DAX, or where in the query to place the clause.