Installation of "Ubuntu 12.04.4-dektop-amd64"??

Ok.. Im lost.. Hope I can get helped. Ive never even seen a Linux before. Ive always been a Windows user, but been curious about Linux though. Please bare with me...

---------------------------------------------------------------------------------------------

MY OBJECTIVE:

 Install and run Ubuntu as my main and only OS, on a blank hard drive. I keep getting a "BOOTMGR is missing" message upon boot. The HD is a replacement & I do not have any Windows cd. This computer is old, and its a hand down. Originally it was owned by my brother-in-law, my father bought it from him later. At the end, I received it as a gift after mine broke. Before giving it to me, he took it to get it upgraded from Vista to Windows 7 Professional 64bit. This means, I do not have any CDs or keys to get Windows OS, or whatever i need from Microsoft. All I have is one original sticker on the bottom of the computer, AND THAT'S IT!

---------------------------MORE DETAILS--------------------------

So... The computer I own, AND WANT LINUX ON, is a DELL Inspiron 1545, whose hard drive completely died recently(this is the soul of the problem).

I decided to use my old laptops hard drive as a REPLACEMENT HARD DRIVE for the dead one in the DELL 1545.

This REPLACEMENT HD has been formatted to NTFS, because for a while, and with an aftermarket hard drive external case, I was using it to store music.
At the moment, this replacement hard drive is completely blank. The music was deleted to use it in the DELL 1545, as the REPLACEMENT HARD DRIVE.

---------------------------Step By Step----------------------------

Downloaded Linux. The download file name is, "Ubuntu 12.04.4-desktop-amd64". (This OS was obtained through the original Ubuntu.com page.) I got a hold of the OS for personal use, and thus burned it to a dvd cd.

With the blank REPLACEMENT HARD DRIVE already in the DELL computer; I booted to insert the dvd with Linux OS, but by this time, the boot screen was done and all I got was a message that read, "BOOTMGR is missing, Press Ctr-Alt-Del to restart".

I went ahead and just closed the tray with the cd either way and waited. The cd-rom was working but nothing happened.

When the cd rom stopped, I restarted the computer (this with the dvd already in the tray) and after the boot screen. The same thing, heard the cd spinning and received the same message. Once I stopped hearing the cd spin or the light blink, i did a restart again.

After the restart, BUT before the boot screen was done, I hit "F2" which is for "Setup", then I followed this path: Settings/General/Boot Sequence. I only left "cd/dvd" highlighted, so it can read the CD-ROM first, rather than the HD.
I thought maybe that might work.

Restarted the machine. I still received the same message, "BOOTMGR is missing. Press Ctr-Alt-Del to restart".

--------------------------------------

Then I thought... I'll use my mothers computer to copy the Linux files from the dvd, to the blank REPLACEMENT HARD DRIVE.

So I pulled out the REPLACEMENT HARD DRIVE from my DELL, then; hooked it up to my Moms computer with a "sata adapter to usb"; Inserted the DVD with Ubuntu OS in Moms vaio, running windows(if that even matters); as soon as the cd is in, I have an option to choose what I want to open the dvd with; selected "Open CD Folders" or something like that; highlighted all the files in the DVD, right clicked, copied; then, right clicked, pasted them to the blank REPLACEMENT HARD DRIVE.

I made sure all the files were transferred by simply right clicking on the HD and going to properties.

I ejected the Replacement HD and put it back in the DELL. (I thought that having the Linux OS saved to the HD, that this would boot it up. Then again, I wasnt sure; but to my logic, I thought, well, Linux has all the files needed to boot.) Im sure that the "MissingBootMGR" just complicated things for me.)

Sooo.... AGAIN, this time with Linux saved in the HD: I rebooted; hit "F2" for "Setup", I followed same path from before: Settings/General/Boot Sequence, except this time, I only left "Hard Drive" highlighted so the computer would start with it first.
The same message after the boot screen appears, "BOOTMGR is missing. Press Ctr-Alt-Del to restart".

_______________________________________________________________________________________________

Since above failed, I ended up restarting the computer again to see if I could give it one last shot. Before the boot screen, I hit the "F12" key.

I receive these 4 options that read as follow:

*Internal HDD
*Onboard NIC
*BIOS Setup
*Diagnostics

I try the first one, "Internal HDD"; I get BOOTMGR is missing. Press Ctr-Alt-Del to restart..

Tried the second one, "Onboard NIC", I get the following:
        Yukon PXE v6.55.1.3 (20080222)
        Pre-boot eXecution Environment (PXE) v2.1
        (C)Copyright 1997-200 Intel Corporation.
        PXE-E61 : Media test failure, check cable.
        PXE- M01 : Exiting PXE ROM.

       BOOTMGR is missing
       Press Ctrl+Alt+Del to restart..

Skipped the third one, "BIOS Setup".

Went to the fourth one, "Diagnostics".
On this one, after running its diagnostics, I got a message stating:

      "No problems have been found with this system so far. Do you want to run the remaining memory test?"

 I selected "YES".

after like 45 minutes of scanning, it finished with a message:

      "Pre-boot System Assessment complete. No diagnostic utility partition identified. Please select OK to reboot your system."

and thats it....

WHAT SHOULD I DO NOW??