Where is your problem? Create a TxxxQuery (or a TxxStoredProc, if you have one), fill it with the appropriate
query statement, connect the dataset to a TFrxDataset (Forgot the exact name) open the designer, assign the data and use it.
There is a menu item 'data' where you can 'assign the data', i.e. like make it visible to the designer.
Another possibility is to directly connect to a database from within the designer.