Installed Sigil but it wont run as it will only allow root to make changes

[andydunne]

I'm running ubuntu 12.04. I'm the only Ubuntu user on a dual boot netbook. I downloaded and installed Sigil with seemingly no problem. But it wont run. when installing i used chmod 755. if I check the properties of the Sigil app for permissions it only mentions root.
should I reinstall with different permission? and how? Sorry for the noob question, still finding my feet with Ubuntu