Mac Xserve OS X Server 10.6.8 Upgrading to 10.11.1

I have just acquired full control to resurrect and breathe new life into an old Mac Server running 10.6.8.

The machine boots successfully and is in good working order running OS 10.6.8 and file shearing to only 1 user. I need to upgrade to the latest supported but compatible OS for this machine so that I can reconfigure and manage the other apple devices and bind open directory accounts and so on.

What is the best way to upgrade this while retaining the file shearing link utilised by the existing user.

Any guide would be gratefully appreciated. I would like to have the latest OS and OS X Server app managing services through this device, Please see full details below.

Model Name: Xserve

Model Identifier: Xserve1,1

Processor Name: Dual-Core Intel Xeon

Processor Speed: 3 GHz

Number Of Processors: 2

Total Number Of Cores: 4

L2 Cache (per processor): 4 MB

Memory: 8 GB

Bus Speed: 1.33 GHz

Boot ROM Version: XS11.0080.B03

SMC Version (system): 1.11f5

LOM Revision: 1.2.8

Serial Number (system): CK74900GV2Q

Hardware UUID: 00000000-0000-1000-8000-0019E3E844EA

Romeo
Nvenet