Do you already have a version of IOS on these devices? Assuming you do and the new code is under 32MB in size then use this command:
copy tftp flash:
(flash: could be slot0: or disk0: etc… depending on hardware, use dir /all to determine the location of your existing IOS image and the filesystem it resides on).
It will ask for the address of your TFTP server and file name to be copied, enter these followed by <cr> each time.
The image should then copy to your device.
If you do not have a TFTP server try Solarwinds, they have a free one, download and install it.
Then you need to either delete your old image:
or change your boot variables to point towards your new version using the command:
boot system flash:new_image_name.bin
This will be different if you do not have an image installed though.
If you don;t have a working IOS on the switch, you will have to use ROMMON mode to upload one.