Can’t install plugins

I have a new WordPress installation on a domain hosted at Dreamhost. I moved my old posts from Blogger and choosed the Mystique theme – which I found in the featured themes. I selected widgets and it was fine. I activated Aksimet, but after that I am not able to install any plugin. I get the sequence of messages

” Downloading install package from http://downloads.wordpress.org/plugin/delicious-for-wordpress.zip.
Unpacking the package.
Installing the plugin.
Could not create directory. /home/movingahead/rohitmishra.me/blog/wp-content/plugins/delicious-for-wordpress/
Plugin Install Failed.

I checked my wp-content folder and saw that the plugin and cache file show owner as (?)(?) while all other folders shown username as the one I use to log onto the server. I tried using SSH to change owner name, and also tried deleting the plugin folder, but nothing worked.

Expecting some experts to help me out.