How do I backup my computers to a custom location?

I have 3 Pcs (all running Windows 7 Pro), and I want to use Windows 'Backup and Restore' to back up each computer to a partition on my main PC.

To be more specific; On my main PC, I have an SSD that holds my OS, and an HDD that I use for file storage. On the HDD (Disk 1), I have made a 200GB partition (Recovery R:\). On the Recovery partition, I have three folders (User 1, User 2, User 3). I want my main PC to backup to the following location: R:\User 1, my second machine to: R:\User 2, and third machine to: R:\User 3.

When I launch Windows 'Backup and Restore', I attempt to change the location of the backup to the above mentioned locations, but I am only able to select the 'R:\' drive, NOT R:\User 1. On the two other machines, I click 'Save on a network...' and only have the option to save to Network Locations like DAVE-PC > Dave or Users > Dave/Public.

The reason I posted this issue in this category is because I believe (for User 2 and User 3 machines) that I simply need to make 'R:\User 2' and 'R:\User 3' Network Locations. I'm not sure resolving my issue regarding User 1 would require the same solution.

Please advise on how to properly configure 'Backup and Restore' via network. Thank you in advance!

*Please note: User 1/2/3 are not the actual names of the PCs I'm dealing with... Just used generic names for simplicity's sake. Also, I did do some searching, but can't seem to locate any relevant solutions to this problem.

I figured this out shortly after posting... I opened R:\ in Windows Explorer, right-clicked on the background and went to 'Share with' > 'Advanced Sharing...', clicked the 'Advanced Sharing' button, checked 'Share this folder', gave the folder a name, clicked the 'Permissions' button and allowed full control for Everyone, then the directories I needed to save to were visible after using the 'Save on network..' button via Windows Backup and Restore.

So one other question; how should I configure the sharing for these directories so that it is not accessible by 'Everyone', just these three PCs?

I've had "addressability" issues with the Win 7 imaging utility using only one computer.
I suggest you use free Macruim or another utility that easily lets you direct images anywhere.
You can find plenty of info on this forum.
Locking up the directory for your use only can be done many ways.
Changing share options before and after your backups might be the easiest.