Best way to share files across computers

Question

I just installed the newest OS X MTLION server. What's the best protocall to share files?

Answer 1

"Didn't work" isn't a problem statement folks here can particularly help with, beyond offering our sympathies.  What is helpful toward getting you to your goals are the particular problems you're facing are your general requirements, and specific details of commands tried and error messages and diagnostics you've encountered.  For better or worse, sharing files is something that both OS X and OS X Server do well, and via a variety of protocols. 
As an example of the sorts of details that can be useful here, the particular volume of data involved is helpful as "large" means something very different to different folks.  The amount of storage and how much it's churning — how often those photos are being added or searched, and how large the photos are, and how many photos are likely to be present in the environment over the years — determines the size of the RAID array(s) necessary initially and over time, as well as helping determine the likely network bandwidth necessary to shuffle the data around should you want or need cloud (off-site) storage for the data, etc.
Based on what you've provided, the "antique" or "classic" solution would be a manually-maintained file server, probably running AFP given you have OS X systems, and either connected by 802.11n (preferably) 5 GHz or (better) gigabit Ethernet.   Larger volumes of data generally mean faster links are needed.  This approach is "antique" or "classic" in that you deal with individual files and directories and related baggage.  Manually.
In a somewhat more modern approach, you'd have a photo storage database package — a content management system for photos — that deals with uploading and indexing and peeking at Exif and related data — and that deals with backups and related processing automatically.  I don't know if such a package exists, but I'd expect it does.
The customized version of this photo storage  — this is a potentially much larger investment on your part, either to write or to have custom built for you, but resulting in a solution for your particular requirements — might involve acquiring development tools such as the FileMaker Pro package and rolling your own storage and retrieval system.  Basically, building your own custom photography database and data management, and using FileMaker or some other database for backups and related processing. 
Better still, a package including billing and related administrivia, etc.  The tedious stuff.
If you're just looking at copying files around for now, then you probably don't have a whole lot of them.  As you do get more photos, then you're going to be spending more time collating and managing the quantities of data and related baggage.  Sooner or later, you'll be looking to automate all of this stuff, and you'll then be looking to move into something that allows you to spend time taking and presumably selling photos, and less time dealing with "files" and "servers"...
As another potential option for learning about some options, see if your Apple Store has some folks that deal with local businesses, and have a chat with them.
Ok, enough of the blue-sky photography-database-management stuff.  
As for copying files around — files containing, well, whatever — that works nicely on both OS X and OS X Server, and some details on exactly what happened when it "didn't work" would be the best approach forward. 
There's a near-infinite number of reasons why computers can fail to perform the desired task, unfortunately.
Permissions can certainly be a factor in file access and file-storage problems. 
FWIW, servers are comparatively more effort to set up, particularly if you're using distributed authentication such as that provided by Open Directory (see Workgroup Manager (WGM) tool) and such.  As for resolving the file access and file sharing problems, some details from the server logs, the file settings and the protection settings tested, etc., will be helpful here in resolving whatever happened.
In general and from experience here in the communities with folks that are experiencing their first server management, you need to get your IP network working, and particularly your local network DNS configured and working.  Weirdness with various services is a common result of network problems and particularly DNS problems.  If (when) the DNS configuration is skipped — as happens far too often — and you later realize it's necessary and start to get DNS working, that tends to get various services, well, confused.  Best to start out with working DNS when you're dealing with a server.  Here's a long-winded write-up on OS X Server DNS services, and which applies to 10.8 server once you click the Advanced settings stuff in the DNS setup in 10.8 Server.app tool. 
Oh, and please don't use .local as your DNS domain.  That causes different-weird.
Welcome to the Apple communities, and apologies on the wall of text.