Installing extra packages for Latex for Gummi app

[sinaphysics]

Hello,
It is one week which I fall in headache and really confused. I've tried a lot to install extra package in Latex and I'm using Gummi distribution of Latex. If you make some help for me in a simple way I would be so thankful.

[sinaphysics]

I use this way and it doesn't work.

1. create a new directory under tex tree

–> sudo mkdir /usr/share/texmf-texlive/tex/latex/<packagename>

2. copy the package inside the new directory

3, run the following command

–> sudo mktexlsr
and when I use Gummi it doesn't work. I use "textcomp" package and I use "\texteuro" but unfortunately it fails.:(