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#111
LAN (Local Area Network) means ethernet, WLAN (Wireless Local Area Network) means WiFi, WWAN means cellular.
It's quite easy and you should be able to find a tutorial online, and possibly a video on youtube. Provided you remember patience, you'll do fine. When opening a laptop, you need to be gentle, and if something isn't coming apart easily, don't force it, as more likely than not you've forgotten a screw. Some laptops open from the bottom, while others open from the top, however all will have screws on the bottom (some may have screws on top, however it's less common, which would be covered by removal plastic trim piece(s)).
You may have an access panel on the bottom of the laptop that provides access to the WiFi card, and I would check before disassembling. You need to be extremely careful when separating the top and/or bottom casing, as there will be flat ribbon cables attached to either. Rule of thumb is once you have the top or bottom casing loose and all plastic tabs released, lift it up about an inch and look under it to see if there's any cables you need to release from the motherboard.
When re-assembling, ensure your firmly seat and lock the cables back on the motherboard. Don't be forceful with the cable lock tabs, but do ensure the cables are seated down as far as they're supposed to go and that they're level. A cable mis-seated/cocked by even a fraction of a millimeter could result in a short circuit, resulting in heat, smoke, or possibly fire. This isn't something to be fearful of, nor should it deter you, as its no different than knowing you need to properly plug a plug into a wall outlet securely before using.