I'll see what I can do to help you. I'm assuming you just want to be able to access the contents of a specific folder on your computer from another Mac, not on the local LAN but over the internet. Those files could then be images or videos that you could view from anywhere.
With those assumptions in mind...
You can do this a couple ways. The first step is going to be getting a DynDNS account and update client. So go to DynDNS.com and get an account and the Mac updater. This way you don't have to remember your home computer IP (which probably changes), you can just have MyName.something.com and that will give you quick access to your home computer from anywhere.
Once you have the DNS set up, you need to set up your computer to host the services you want. I feel that the simplest ways are going to be using Web Sharing or SSH (would include SFTP).
To enable these
http://www.woopid.com/video/865/Enable-Web-Sharing or
http://www.woopid.com/video/863/Enable-Remote-SSH-Login will tell you what to do. Here are the advantages and disadvantages of each.
If you go with SSH you will need an application to pull the files off of the remote computer and put them on your local. The bonus is that this is a SECURE connection that is password protected with your home computer's login. You also will have access to ANY files on the entire computer. So you can have your files anywhere.
If you go with HTTP (Web Sharing) the connection is open and anyone would be able to get read access to these files if they knew the address. Also any files you want to access need to be in a shared location.
If you enable any of these you will have to enable port forwarding on your router. You can probably google your router to find out how, but SSH is port 22 and HTTP is port 80. So those are what you'll need to enable. You'll understand when you find out how port forwarding works.
Now I'll assume you have your service of choice (I actually have both) enabled and the ports forwarded.
If you're using SSH you can just connect with an SFTP client like Fugu or Fetch to your new DynDNS domain that you set up at the beginning and log in with your server's login name and password and download any media files you want to view.
If you are using HTTP you'll have to add the files to your shared folder. I always forget where that hosted folder is but you can put any file you want in there and it will technically be hosted. Then you'll have to remember the address to the file or create a small page that you can view with links to all the files that you want access to. The advantage of this is that you can view these from any web browser and not have to use a specific client.
This is a very rough guide but it should get you started. If you have specific questions you can ask here.
