Well, if you know how to connect two computers under 9.2, it's pretty much the same between 10.2 and 9.2. You'll need an ethernet crossover cable to connect the two computers. Then, make sure "Ethernet" is selected in the AppleTalk control panel on the iMac, and that AppleTalk is active in the Network preference pane on the B&W G3 tower.
After doing that, enable file sharing on one of the computers (use the Sharing preference pane for the tower, or the File Sharing control panel for the iMac), and use the other to connect to the other computer.
If you're connecting TO the iMac FROM the tower, just press Command-K in the Finder, and then double-click your iMac computer name in the list (you may need to click on either "AppleTalk" or "Local Network" in the first column). Enter your login and password (defined in the File Sharing control panel on the iMac), select your hard drive, and then press OK. Your iMac's hard drive will mount on the desktop, and you can transfer files as you wish.
If you're connecting to the TOWER from the iMac, then you'll just need to use the Chooser instead under OS 9. It should be under the Apple menu. Click "AppleTalk" on the left side, and your tower's computer name should show up on the right. Double-click it, enter your login and password, select your hard drive or home folder, and press OK. Then transfer files at will!
I hope that helps.