You can retrieve a breakdown of ethnicities in attendance at your school by running a School Summary report.
Please go to Reporting > Reports > Students tab > School Summary, and check the "Ethnicity" box option before clicking "Submit":
TIP: You can use the Print and Download icons in the top righthand corner of the page to either print out or digitally export the data. Click the relevant icon to print, and for exporting, also select the file format and page orientation: