connecting APRS is almost identical as setting up a "Packet Station"
Each configuration is going to depend on the hardware you intend on using.
For example: Are you going to use a TNC or just a Soundcard interface? Do you want to use a laptop or a palmpilot?
Are you going to use a live mobile GPS or have a home based "fixed" position to report? (ie: home based weatherstation) What model GPS? What kind of serial output port does it have? Can it communicate with your APRS software in the same language?
Are you going to use a laptop in your car for "reading" other people's position while travelling, or do you just want a way to send out and report your position only?
These and many other considerations will determine how everything is going to be connected together.
I would suggest reading the following website and consider your available options before moving ahead:http://www.tapr.org/tapr/html/pktf.html
Charles - KC8VWM