Put flickr / photo album – What is a good way to put pictures/album?

Hi there,
I finally done with installing WordPress. Because of its simplicity, I would like to add pictures in it (like phot album that I can refer to. Afterbrowsing themes, I’m not really sure if pick one good theme that can put a lot of pictures would be good. (If you know such template, please let me know)
So, i was surfing about putting flickr into WP. and I downloaded ‘Flickr photo gallery; and ‘exec. php’. I also downloaded ‘duh gallery’ and put them in the plugin. However, when I try to click ‘photo album’ tab, it gives me this permission error: This plugin requires that the directory /var/www/vhosts/example.com/subdomains/blog/httpdocs/wp-content/plugins/flickr/flickr-cache/ be writable by the web server. I contacted the server and they said they already give permission 755. Is there any other specific requirement does it need, becasue it still doesn’t work.
Thank you so much in advance and so sorry for the lack technical term as I’m new at this.