That's incredibly vague, not even a tiny fraction of what is necessary for us to help you. You should give a laptop model # and clarify whether you are looking for audio connection, video connection, or both (or something more esoteric like automation/control/firmware update). List what sort of video & audio output jacks the laptop provides, and if you are asking about video give the model # of your TV/projector and what video inputs it has.
I will take a wild guess, and imagine that you want to connect a computer to the Denon so that you can send control commands from the laptop to the Denon. To do that, all you need is a serial cable. It is possible that you might also need a "null modem adaptor" at one end of the serial cable.
If you were hoping to send audio or video, the serial cable is not going to do that.
And...of course you will need some kind of software on the laptop to communicate with the Denon. Can't help much there...it could be simple, or somewhat tricky. for example: good old Sony laserdisk used the command "OP" to open the laserdisk tray, and "PL" to play the disk. Nice, easy. Some other gear I had needed a convoluted bunch of cryptic numbers to do the simplest thing.
Actually, its rather simple to control the 3808 over your network from your pc or laptop. All you really need is your IP address for the 3808 on your network, and you can control basic things like volume, muting, inputs, etc. No additional software necessary. It really depends what you want to do with it.