The chmod command allows you to modify file and directory permissions.
and Google are the best sources for more information and examples. I don't what 'apache permissions' means.
Looks to me from what you've posted that you should be able to write to the html directory as the webftpaccount user. Do you receive any error messages?
Are you aware that FTP is an insecure protocol? Your username and password are sent in the clear. You should not use FTP unless you really have no other choice. If you have SSH access to the machine you can use SFTP for file transfer and should do so instead of using FTP.