How can I open several sites

I guess there's an available add-ons for mozilla for this kind of problem, the add-on is called linky, not sure if this works, haven't tried yet.
 Linky is an add-on for mozilla, for you to use this, you should have mozilla installed in your system.
May I know the site where I can download this add-on, by the way, I'm currently using opera as my default browser. Does it have the same capabilities like of mozilla (to open several tabs at a time)?
Go to this link and try to install the Linky add-on manager on Firefox. Not sure with opera, not familiar with the browser though for I’m using Firefox as my default browser.
After you installed the add-ons into Firefox, you will need the list of site which you want to open all at a time. If it saved in excel, open the file and resave it again as webpage. After that, open the webpage and highlight all the links then right click, you should see "Linky". Click on that and press ok, after that, all highlighted sites should be opened automatically "all at one time". Hope this helps.