Though I do agree that knowing what software you are using would definitely help. Knowing what computer hardware you are using would be really helpful, too.
There are at least four ports on the miniDV based camcorder. One is for power... the others:
The AV port is normally used with a cable that came with the camcorder that plugs into the camcorder on one side and has a yellow RCA jack for video - and a red (right - or mono) and white (left ) RCA jacks for audio. This is normally used to connect the camcorder directly to a TV to send signals from the camcorder to the TV (or VCR). This can sometimes (depending on the camcorder) be used to connect a VCR or other video source to get signals IN to the camcorder. This is an analog signal. Yes, the video will not look very good if this is the transfer method used.
The USB port is normally used with a cable that came with the camcorder that plugs into the camcorder on one side and the computer's USB port. This would be used to transfer stills from the camcorder's memory card.
The DV port is normally used with a cable that was purchased separately from the camcorder because the camciorder manufacturers typically do not include this cable in the box with the camcorder. Firewire, i.Link, IEEE1394 are all the same thing. This connection is used to transfer movies from the miniDV tape to or from the camcorder or to or from the computer. Apple Macintosh computers have had Firewire ports for years - Most traditional windows machines do not include a Firewire port - though it is starting to become a little more common. Generally speaking, however, a Firewire/i.Link/IEEE1394 port would need to be added to the Windows machine.
If the video was shot using SP mode on the camcorder, it is possible that the video will not look very good. It is recommended that the LP setting on the camcorder be used when capturing video to miniDV tape. It is also recommended that miniDV tape not be re-used. Once the tape has recordered video, look the tape, mark it using the included tape labels and a pen... and use a new tape.