Error after upgrading to 3.2

This is a known issue – you need to update the theme or make a manual fix. Read here for instructions:

http://wordpress.org/support/topic/troubleshooting-wordpress-32-master-list?replies=7#post-2201144

FTP is a way to send and retrieve files from your server. You can read more here: http://codex.wordpress.org/FTP_Clients

You can download the fixed Arras theme here: http://www.arrastheme.com/forums/topic7004-arras-theme-151-now-available.html

If you’re not comfortable updating the theme yourself, you might want to hire someone to give you some hands-on help. You could look for a web developer in your area who works with WordPress, or post a help wanted notice here: http://jobs.wordpress.net/

I presume there was some sort of technical conflict between the way the Arras theme was coded and the new version of WordPress. To know the details, you’d need to ask the Arras theme makers.