Workbench 3.0/3.1 has no TCP/IP stack, browser, FTP client or anything that even remotely supports networking.
Workbench 3.9 added AWeb and TCP/IP stack but you need a CD-ROM drive to install it. Standard Amiga 1200 case has no room nor connectors for the drive.
To use PCMCIA network card you must download CNET driver from Aminet which you must somehow move to your Amiga. Luckily Amiga can read PC formatted disks but you are limited to 720kB DD disks. Not every user know how to use HD disk as DD or have friends with an old PC.
It is tricky. The hardware is so incompatible with current standards. Hardcore Amigans have Catweasels, parnets, USB extensions and what not... but beginners are struggling with this stuff.
Seems that people forget that getting files to your amiga to get started is easier then you think, lets say you got an A1200 with 2,5" HDD and no means to use the drive on your windows/linux machine or the know how to do it and you do not have an CF->PCMCIA adapter and your A1200 is stock, how do you do?
Easy, null-modem serial cable. Easy as pie and have been used for ages, build or buy a cable for scraps, plug in to a PC then your Amiga, and nowdays it's as easy as download and install the free version of Amiga explorer. Bam easy to use and you can even pick any ADF you got on your PC drag/drop and write to disk on Amiga (provided it got enough memory but that is no issue with the 1200 with DD floppies).
I have used a null-modem cable to copy over files even to my old Amiga 500 (with 512KB trapdoor expansion), that was how I made new WB disks when problem arised and I had no HDD on the Amiga.
This is a easy way people tend to forget and requires just a cheep cable and it's not even hard to build yourself and there is no problem to find the pinouts to make one.
Sure not the fastest way but it works. And if I do not remember wrong it's quite well explained on Amigaforever?