Access computer behind firewall from outside

[Mayank Jain]

Hi
I am relatively new to iptables and i have querry. 
I want to access my Fedora 3 home machine , which is behind a red hat
7.3 firewall running iptables, from computer at work place. i want to
be able to access at work some files i have on my home computer. i
have a DSL connection, so iam practically always online. i have one
public ipaddress at the firewall end. inside of the firewall, i use
private ipaddresses. there are 10 other computers in the network but i
just need access to my one computer.
how cud i get around to doing that? does the solution depend on the
type of service i want to access, like for ex. ftp, http, file
sharing?
also, i wud like to know which file shud one edit to add iptable rules.

thank you,
Mayank.