Hmm.. can we see the snapshot of the whole back panel when you have opened it? Just the part that you could open easily. The card may not be exactly same in shape or size (the ones listed on the page were all "half sized" cards), but it must be there somewhere. Also, it is accessible in *most* laptops, but not *all* (like some HCL Emachines). So it is possible that your model does not provides user access to it. A snapshot should tell us everything regarding that.
For creating bootable USB, you may also try Unetbootin (most recommended here), or if you are running some version of Ubuntu, you can use its native "Startup Disk Creator" program to create the Live USB. My preferred way is to boot a Virtual Machine (on VMware or VirtualBox) > attach the target USB to it and let it get detected by the VM > use the Live Session in the VM to run its Startup Disk Creator program to create the Live USB. This ensures there are no issues due to version difference.
Another simple method (if you are running Ubuntu) is the dd command. It is a bit risky in the sense that if you used wrong device name as target, it will be permanently overwritten. So be extra careful with this. Assuming your USB drive is "/dev/sdx" (confirm by seeing the output of "mount" command) -
Change the 'x' with whatever letter has been assigned to your USB drive.
sudo dd if=<the path of your iso file> of=/dev/sdx
I wouldn't advice taking your laptop apart unless you have experience of doing that. A cheap USB wifi dongle can be found for less than $10 on ebay, while replacing a broken case would cost much more than that.