In report builder, you will find two main sections for any report: the data model, and the layout model.
In the data model you define (among other things) the queries that will get the data from the database, and in the layout model you define how the data will be presented to the user.
The first thing you need to do, is modify the query in the data model, in order to get the 2 new fields from the table.
Then you need to go to the layout model, and define 2 new items (Text fields), putting them in the position in which you want them to be displayed. Then, for each one of these items, open the property palette (by double clicking on the item), and change the “source” property, selecting the name of the new column created in the data model when the query was modified.