Old PCs could format floppy drives to the lower format DD instead of the HD so first you need to format a disk to the lower density drive so it can be read on the A500. Then simply use the 850MB floppy to store your information on the PC. Then obtain a copy of CrossDOS that can be run on the A500. This is the chicken and egg thing cus it is no use that being on a PC disk because you need to mount it and without CrossDOS you can't. At times like this it helps to know someone that can send you DD disk with it on. Where are you ?
Once you have Workbench loaded and clicked to mount the PC drive as your floppy drive from the CrossDOS software you can simply copy the file and then through disk swapping get it onto a DD disk. I do believe expanding the machine with a modest trapdoor RAM card could be helpful.
What I actually do is run a Parnet cable between the Amiga and the PC and run a small piece of software so that the machines can talk to each other. Bit slow, but actually does work. Most of the A500 stuff was for a single floppy disk so memory isn't that much of a problem. Parnet software is still on Aminet, though you need the cable.
Un-archiving involves software like a good DMS tool in C and also LHA in C and knowing what to write from the shell to fire them up. Knowing a friendly Amigan that can let you have a copy of these on a DD helps.
Once you get past the initial and start building your tools and floppies and understanding the way the Amiga works even with a single drive floppy unit then you simply go back to a time when this was the norm. Also try and get a second floppy drive and see if you can get the HD bigger capacity one. Then get an external hard drive sidecar and you will really start to enjoy the computer. Great fun.
Have a read on this
http://aminet.net/package/comm/net/ParBENCH31There is a tutorial on my website regarding creating self booting disks which is fun though you need understand about firing up the shell.
