accidentally downloaded weatherblink and now it keeps opening whenever I open a new tab

My mom accidentally downloaded something called weatherblink. It change her home as well as changing the tab settings in firefox. I searched to see if it is in the downloaded apps in the start/programs to uninstall it, but it is not there. How can I fix it where when opening a new tab, it does not take me to weatherblink. I want a new tab to open in Yahoo.com. Thank you.