I have a mac desk top OS X version 10.6.8

How far will depend upon the specifications of your computer.

Get more information about your computer. Go to the Apple in the upper left corner of any window, then "About This Mac". Write down, or highlight and copy, what it says about "version"and report that here. Now continue to "More Info..." Copy and paste the information here, but omit the serial number and Hardware UUID (if present).

For any version it is advisable to use Software Update at least once so you get special updates such as the "Mac App Store Update for OS X Snow Leopard" - https://support.apple.com/HT205702

Model Name: MacBook

Model Identifier: MacBook4,1

Processor Name: Intel Core 2 Duo

Processor Speed: 2.4 GHz

Number Of Processors: 1

Total Number Of Cores: 2

L2 Cache: 3 MB

Memory: 2 GB

Bus Speed: 800 MHz

Boot ROM Version: MB41.00C1.B00

SMC Version (system): 1.31f1

The highest Mac OS X version that MacBook can upgrade to is paid upgrade to OS X 10.7.5 Lion.

But in my own experience, it isn’t really worth it.

You are better off staying with OS X 10.6.8.

To be a litle more secure on that old MacBook, you should STOP using that very old and very unsecure version of Apple Safari.

The ONLY more recent, third party web browser available for OS X 10.6.8 is Mozilla Firefox ESR version 45.9.

It’s a nearly year old version of Firefox, but it is still much more recent and more secure than that nearly 7-8 year old version of Apple Safari.

Switch to using Mozilla Firefox ESR version 45.9 found here.

This is a more recent, more secure web browser for OS X 10.6.8.

Firefox 45.9 ESR .dmg install file here.

https://ftp.mozilla.org/pub/firefox/releases/45.9.0esr/mac/en-US/

Dbl click to download, locate the Firefox 45.9 ESR.dmg on your Mac.

Dbl click on the file and it should put up both a disk drive looking image and a pop up installation window.

Drag the Firefox Application icon into the Application folder shortcut icon in the same install window.

The go to your Applications folder, find Firefox, the launch it!

You may need to update Adobe Flash Player to the last compatible version for Firefox 45.9

You need to use Adobe's Flash Player uninstaller, first, to uninstall the older Adobe Flash Player.

https://helpx.adobe.com/flash-player/kb/uninstall-flash-player-mac-os.html

On the Adobe Flash Player section of the Adobe website, you will need to look for the last Adobe Flash Player version compatible with Mozilla Firefox 45.9.

This is the Adobe Flash Player you are looking for on the Adobe web site.

Adobe Shockwave Flash version 26.0.0.137

Look toward the bottom half of this webpage link.

https://fpdownload.macromedia.com/pub/flashplayer/installers/archive/fp_26.0.0.1 31_archive.zip

Once downloaded on your Mac, dbl-click to open the zIp file

Dbl click to Install the Mac OS version if there is one listed in the archive file (might be a .dmg file).

When you open that Adobe Flash Player archive file, it will create an archive folder.

Dbl click that folder, two other folders will appear.

Click the first folder WITHOUT THE words debug in it!

When that folder opens you are looking for a Mac OS .dmg file with this name

flashplayer26_0r0_131_mac.dmg

Dbl click on this and begin the install procedure from the brownish red Adobe install folder that appears.

Good Luck!