I presume that you use the PCIe -6259 board that has 3 digital ports: port0 (32 lines), port1 (8 lines), port2 (8 lines). When you configure the NI Port element in Event and select the port0, you need also change the 'Pin Number' property from 8 to 32.
Then you will be able to write 32-bits values in that port via the 'Output Value' property. If you do not see the 'Pin Number' property on the NI Port element, you need to update EventIDE to one of the newest version. You can get the latest version on www.okazolab.com/download