First of all you need to make sure that the PC is online with the PLC, check this under the File -> Project -> Set, drop down menu, select the PLC tab and check that the Mode says online, if it doesn't, highlight the mode and press the F3 key.
To upload the program block from the PLC, again use the File drop down menu option. File -> Blocks -> Transfer. Then in the transfer blocks screen, you will want to transfer from the PLC to the program file, in the selection window, select block list and type in A for all blocks.
Paul