It's 'CHMOD' not 'CHMODE'.
Use a standard FTP program, one either built into your web design tool or an FTP client such as WSFTP, Voyager, etc.
Connect to server, browse to the directory your file is in and highlight the file or directory you want to CHMOD. Depending on the FTP program you are using, you can right-click, look for a button, look for a window or anything else that is labled 'CHMOD'.
From there you can set your permissions to whatever you would like. You probably want to CHMOD your file and the directory it is in to '755'. You can do '777' which will fix your problem, but may pose some security risks.
If you can't CHMOD by number, some clients have check boxes. Clicking on all nine of the check boxes will modify your permissions to '777'.