Yes you can do that with subdomains.  Just set up an ftp account with the name of the subdomain.

For mykid1.yourdomain.com it would be:
FTP user: mykid1@yourdomain.com
passsword: you set
host: ftp.mykid1.yourdomain.com (or just the subdomain name without the "ftp.".

Best thing is to make a directory inside your public_html named the same as the sub (mykid1).  Then create your subdomain, give it a minute, then create your ftp account.

As for acces, you can click on 'web protect' in the CPanel, and drill down the directory you want authorized access to (for http).  Just follow the directions.
 
 [ April 05, 2003, 12:32 AM: Message edited by: TWebMan ]

You have to buy ftp accounts to go with the subdomains.

(unless you have the premium plan which already includes some extra ftp usernames)

5 additional ftp accounts costs $1.95/month