how does this work?

Okay so i bought my RN 104 a while back and slapped 2 3tb wd reds in there in raid 0, now i would like to use it to back up my data in my computer.

i started by going to the readynas admin page for my nas then i went to backup and created a new backup job. now this is where i got stuck with roaming the internet for any useful information at all because i couldnt find ANYTHING in the manual that actually explained how to do this, all i got from it is that your source is the data you want backup and destination is the path where it gets backuped too.

now there are so many options to use here and i have no idea what to do..

all i want is to backup the I:\ and S:\ drives to my NAS but all that ive tried seemingly only bring up errors like "error backup job 'xxx': source cannot be mounted on the system" and error backup job 'xxx': source path does not exist.

is source host supposed to be my ip? my computer name?
is path supposed to be the network path to my harddrive? or I:\ (//computername)?

its so confusing and there doesnt seem to be even any guides out on youtube.