You can ftp the files into which ever directory it belongs in.
For example:
If you are adding a Counter-Srike: Source HLTV file
Compress the file to save space and time.
Upload the file to the "/demos/counterstrikesource/hltv/" directory
Edit your mysql database with the following code:
INSERT INTO seco_demos VALUES(0,"myfile.zip","Counter-Strike: Source","HLTV")
You MUST follow the team naming conventions.
If you used a different template database prefix other then the default "seco_", use that instead.
Replace the number "0" with whatever number would be after the last item in that table. "7" should be the highest value, so re-order them as you see fit. the lower the number, the higher up on the list it will be with "recent demos."
Rename "myfile.zip" to whatever your demo is called.
The two demo types are "HLTV" or "POV" and YES they must be in all caps.
Tell your friends to watch the demo where your team "pwns" some other team.