Normally, FTP access is not controlled by the Apache (web server) htaccess file. The FTP server’s ability to write (and subsequently your ability to write) to a directory is controlled by the directory permissions.
When you connected via FTP or SFTP (assuming that you did not do it anonymously) then your account information’s user and group IDs that you used on the FTP client, Filezilla, are matched against the directory. (Write access to a directory is controlled by the directory and not the file.) So, if you secured the directory with a mode that does not permit you to write then you can’t write.
Make sure that your directory is mode 755 and is owned by you. If you do this then you should be able to write to that directory.
You can find out all about directory permissions, file permissions, mode settings (as in chmod) in most newbie guides to UNIX or simply searching the internet. There may even be articles in the wiki here. But, the .htaccess file has NOTHING to do with FTP. Don’t change the .htaccess file, even for your window, and expect that it will permit you to use FTP. It won’t.