Text widget coding errors

Help! I was trying to add the code for a “grab my button” in a text widget box and I got these errors:

Warning: array_keys() [function.array-keys]: The first argument should be an array in /home2/thejoyfu/public_html/wp-includes/widgets.php on line 686

Warning: Invalid argument supplied for foreach() in /home2/thejoyfu/public_html/wp-includes/widgets.php on line 686

Warning: Cannot modify header information – headers already sent by (output started at /home2/thejoyfu/public_html/wp-includes/widgets.php:686) in /home2/thejoyfu/public_html/wp-login.php on line 267

Warning: Cannot mod

Now I can’t even use my WP control panel anymore. I use Cyberduck through BuleHost to manage my files, but I don’t know how to get to the lines that are in error and how to fix them when I get there. I have found the file /home2/thejoyfu/public_html/wp-includes/widgets.php in Cyber duck, but then what?

Where do I start?