How can I install OS X on my used Mac?

[mhelseth93]

My friend has a job where he finds cool stuff all the time and gets to take it home. He recently found a mac computer and we re trying to get it up and running again.

On startup it loads OS X Utilities and prompts me to:
-Restore from time machine backup
-Reinstall OS X
-Get Help Online
-Repair and Disk Utility

out of those options, the only one that gives hope is Reinstalling, but after entering my Apple ID it doesnt seem to accept it.

I believe this is because the original owner had a digital copy of OS X bought from the mac store and I can only reinstall using that Apple ID.

The big problem is, in this startup mode that I m stuck in, I cant download the Apple App store to buy/download the OS.
(When I tried, it said I didnt have enough disk space, even though all hard drives are empty)

What steps can I take to get the OS linked to my Apple ID, or am I able to download the app store a different way? I am just looking for a way to get this computer to be usable, I dont mind buying the OS but I don't have another mac to access the App Store from.

----EDIT-----(including specs)
The computer is an iMac Core 2 Duo, 24 in (All-in-one), 2007 model
Currently It is running 10.8 Mountain Lion but has a second hard drive directory for Snow Leopard.
Has an Intel Core 2 Duo processor
Radeon HD 2600 PRO GPU
1 GB of Ram

Heres a link for more specs if needed http://www.everymac.com/systems/apple/imac/specs/imac-core-2-duo-2.4-24-inch-aluminum-specs.html

 

[chscag]

It would be a lot easier to help you if you had provided us with information about the Mac you're trying to get working.

Year and model? What version of OS X is it currently running? If you don't know the year and model, check the serial number and do a Google search for a site that will translate the SN into what Mac you have.

 

[mhelseth93]

It would be a lot easier to help you if you had provided us with information about the Mac you're trying to get working.

Sorry about that, I thought I included the OS version, but now both are in there, thanks!

 

[chscag]

Purchase a copy of Snow Leopard on DVD from the on line Apple store ($19.99) and use it to boot and wipe the iMac. Install Snow Leopard and then update Snow Leopard to 10.6.8 (free from Apple). After that, you can download a copy of Yosemite (free) from Apple and install it. However, before installing anything you need more memory. That particular iMac can take 6 GB of memory. (one 4 GB module plus one 2 GB module)

 

[harryb2448]

Must be using invisible ink?

 

[MightyGem]

Must be using invisible ink?

Yes. Is there a reason why the first post isn't showing.

 

[pigoo3]

Yes. Is there a reason why the first post isn't showing.

It should be visible now.

- Nick

 

[chscag]

Must be using invisible ink?

We keep telling you not to forget to wear your magic glasses Harry. But since you forgot them, Nick had to perform some extra moderator magic to make it visible for you. ;D

 

[pigoo3]

Yeah…OP was using invisible ink! I had to spritz some lemon juice on it to make it visible!

- Nick

 

[MightyGem]

So why wasn't it showing? I've noticed this on other occasions.

 

[pigoo3]

So why wasn't it showing? I've noticed this on other occasions.

When new/newer members make a post with a link…the post is flagged & needs to be approved/checked/investigated.

- Nick

 

[MightyGem]

Thanks.