This is my first network that I have made, and I have virtually no idea what I'm doing. I understand the basics like IP addresses and getting the Ether cards working.

It's over a Win98 p350 and a Slackware 486DX33. The network cards are EXACTLY the same except ones PCI and the other is ISA, 3Com 3C5098 I believe. I have connected them and I can ping and FTP over them (using FTPd on the Linux computer) but when I try to PPP on the Linux computer, it wont do anything. Can't find host name. Maby because it tries to find the server accross the network and not the net? How is this fixed?

Plus I would like to be able to have a modem on the p350 and be able to access the net from my computer (slackware 486) at the same time, so I don't bother everyone when I need to use the net.

THX 1.0E+10

Not sure what you mean. I guess you have a modem (or other connection that uses PPP) and try to connect. Make sure you have /etc/resolv.conf and that there are your nameservers. The lines have the following format: "nameserver dnsiphere".
To share a connection you need a simple firewalling script (masquerading). Examples are posted to this forum very often, so search and copy one of them.