Need help for mac

I have a two year old mac 10.5.8. I have plugged this in and searched the web for how to use the product but am still at a loss. Im sure its much easier than I am thinking it to be but I would really just like to use the hard drive as almost a zip drive. To store certain information and not have to go through setting up software to categorize my files, etc. Every time i run the software my computers fan goes through the roof and i can’t seem to get anywhere. Is there a way I can use this device without the software and just drag and drop the files I want stored in it? thanks so much

What external do you have?