MAC HD FULL!! HELP!!

Please! Complaining? This is a common problem with all operating systems on all computers. Please be more informed if you plan to complain.

If you can access and backup your files then I suggest you do so. If you are still able to delete files, then see the following:

How to Free Up Space on The Hard Drive

1. You can remove data from your Home folder except for the /Home/Library/ folder.
2. Visit The XLab FAQs and read the FAQ on freeing up space on your hard drive.
3. Also, see Freeing space on your Mac OS X startup disk.
4. Free up storage space on your Mac.
5. See Where did my Disk Space go?.
6. Be sure to Empty the Trash to recover the space.
7. Replace the drive with a larger one. Check out OWC for drives, tutorials, and toolkits.
8. Use OmniDiskSweeper or GrandPerspective to search your drive for large files and where they are located.

If you have access to another system then it may be easier placing your iMac into Target Disk Mode, essentially turning it into an external hard drive that you can connect to another device so that you can move the file. Target Disk Mode would allow you to backup your files to another volume, or locate and delete files that you know are safe to remove. Obviously you want to be very careful that you don't erase system files, however you should be able to look through your user account folders and delete unneeded files such as applications that are no longer used.

How to use target disk mode to move files between two Mac computers - Apple Support

If you have no free space on the drive then your only option is to erase the drive and install macOS. You cannot recover your data as it is all lost at this point.

Install El Capitan or Later from Scratch

If possible backup your files.

1. Restart the computer. Immediately after the chime hold down the CommandandRkeys until the Apple logo appears. When the Utility Menu appears:
2. Select Disk Utility from the Utility Menu and click on Continue button.
3. When Disk Utility loads select the volume (indented entry, usually Macintosh HD) from the Device list.
4. Click on the Erase icon in Disk Utility's main window. A panel will drop down.
5. Set the Format type to Mac OS Extended (Journaled.)
6. Click on the Apply button, then wait for the Done button to activate and click on it.
7. Quit Disk Utility and return to the Utility Menu.
8. Select Install OS X and click on the Continue button.

This will install the version of OS X you had installed.

If Time Machine cannot find a backup drive it is because you don't have one or it isn't connected to your computer.

When a drive becomes full macOS cannot extend the directory space because there is not enough contiguous space on the drive for the extension. This causes a loss of the directory and all file operations. This is a catastrophic event. If you need to recover your files then you need to remove the drive, place it in an external enclosure, then use file recovery software to attempt restoring your data. See the following:

General File Recovery

If you stop using the disk it's possible to recover deleted files that have not been overwritten by using recovery software such as MAC Data Recovery, Data Rescue II, File Salvage or TechTool Pro. Each of the preceding come on a bootable CD to enable use without risk of writing more data to the disk. Two free alternatives are Disk Drill and Cisdem DataRecovery. Recovery software usually provides trial versions that enable you to determine if the software would help before actually paying for it. Beyond this or if the drive has completely failed, then you would need to send the drive to a recovery service like Drive Savers, which is very expensive.

The longer the hard drive remains in use and data are written to it, the greater the risk your deleted files will be overwritten.

Also, visit The XLab FAQs and read the FAQ on Data Recovery.

No. As I explained, once you have reached this point you no longer can access your files except by using recovery software to try finding them and copying them to another drive.

All that I have related to you is based on your original post, "Im not even lying when i say i have 0KB free space."

Yes...

You can use the Time Machine app in your Applications folder to backup data to your WD.

How to use Time Machine to back up or restore your Mac - Apple Support

I believe if the OP truly has no free space available, then Time Machine cannot backup the drive. At this point the drive is unusable because its directory has been garbled.

Oops! Forgot this:

You need to maintain a minimum of 20GBs or 10% of the drive's capacity, whichever is greater, as free space.