You have three ways to do it:
1. Place everything you want in a .zip file, and attach it to your post. The advantage of this is that you can keep track of it more easily and delete it when you make a new version or something. You can also keep track of how many people downloaded your file with this. Downside is that there's a file size limit.
2. Place everything in a .zip file and upload it to the civfanatics server. Do this by going to the bottom of the page, and there's a bar of links, one of which is "Upload File". Follow the instructions, then get the url of your file and put it in your post, using BB code to make it a link, or just having the url itself. Upside is no server-imposed size limit. The size limit is more than the attachment size limit. Downside is that if your file is too big, you'll be an evil server clogger.
3. Upload all your stuff somewhere else and link from there. Upside is that there are no limitations placed on this by CFC (unless it's a legal matter). Downside is that it's a bit of trouble.