I'm not going to give you an idiots guide, but I can tell you that in order to get those ADF files working on your Amiga 500 you need one of two things :
Either an harddrive or a lot of ram; I don't think that 1 MB will be enough.
The reason is that first of all you need to transfer the file to the Amiga. It could be done with a null-modem cable, connecting the A500 with your PC, but the Amiga has to have Workbench loaded which occupies the first 200-300 KB of your ram. If you succed in getting the network up and running you need some space for the ADF file, which will be placed in the RAM disk. In other words, if you copy a file it may not be bigger than the available amount of ram, which should be 700 KB at this point (1 MB minus the 300 KB for running Workbench). At last you need to have some RAM for decompressing the ADF file to an Amiga disk. Keep in mind that you also need some extra RAM for the networking software, so anything less than 1.5 MB isn't worth spending time on if you ask me.
If I were you I would get an harddrive for the A500. It will give you some needed RAM and a lot of storage space for the ADF files. Furthermore you can easily connect to the PC when you have setup the networking software for good.
If a harddrive for the A500 is out of the question, then get an A1200 with a small harddrive. On this one you can make a 720 KB PC disk and copy an ADF file to disk, and copy it to your Amiga harddrive afterwards, and then decompress it. The ADFs prop need to be compressed a bit for fitting the 720 KB disk. You could also just hook the A1200 up to the internet and download the files to it, or make a network with the PC.
Overall I would go for the second solution as it's far easier than the first one, and I'm sure also less expensive.
EDIT : Damn, beaten at the finish line :-(
