Windows 10 Backup Program

Thanks to everyone who responded.. Apparently a backup is not what I really needed for keeping files (several generations back) up to date but rather File History.. Again, Win 10 file history function appears to want a drive that is not being used ba any other program to set it up. Here is my new question?? I have a USB Hard Drive attached to my PC with two large (500GB) partitions on it.. which each one less than 25% used..While this drive is in service, can I split one of the existing 500GB partitions into 2 x 250 GB partitions?? thus giving me an un-used drive (partition) to use for File History. I have Googled this question but flooded with responses that urge me to buy this or that partition program.. Maybe the answer is just buy another new drive.. Thanks again for all of your responses.. Making life much easier for me..