If you installed WordPress through the application vault your plugins would be in: /webspace/siteapps/$ID/htdocs/wp-content/themes/
If you installed WordPress through the application vault your plugins would be in: /webapps/$ID/htdocs/wp-content/themes/
Where $ID is the four digit install ID located to the left of the install name in the Application Vault. Typically we recommend any plugins or themes through the Application Vault itself by clicking on the Installation name.
Simply download the file(s) you wish to edit. Make any changes you want and upload them again. NB: These files contain the code for displaying your blog's entries etc., so do not remove existing code unless you know what you are doing. You also might have issues replacing these files as they might be owned by the webserver user.
Note: You might not be able to modify these files via FTP as they may be owned by the webservice user (if WordPress created them initially). You might have to download the entire theme, make the modifications, and re-upload the entire theme through WordPress to make changes or else contact us.