setting up my computer as a slave drive.

my hard drive won't mount. before i buy data recovery software, i want to make sure there is something worth recovering. i downloaded a free trial to my laptop, but i don't know how to connect said laptop to my desktop. i want to treat my desktop as an external hard drive (my uncle called it a slave drive) and see if i can recover anything with the trial software on my laptop.

how would i go about connecting the two computers? i know it can't be as simple as just running an ethernet cable between them. any help would be greatly appreciated.