I don't know how Tamil Fonts can be installing in Linux System? anybody can help me pls

Welcome to LQ.

No tamil fonts for a contemporary Suse, AFAIK.
( Suse 9.x, Suse 10.0 : fonts-tamil-<version>.noarch.rpm ).

Any tamil font package can be used : You can find fonts with Google.

The easy way : Use Fedora packages.
1) su <password>
1a) rpm -Uvh fontpackages-filesystem-1.44-3.fc17.noarch.rpm
http://dl.fedoraproject.org/pub/fedo...c17.noarch.rpm
2) rpm -Uvh samyak-fonts-common-1.2.2-6.fc17.noarch.rpm
http://dl.fedoraproject.org/pub/fedo...c17.noarch.rpm
3) rpm -Uvh samyak-tamil-fonts-1.2.2-6.fc17.noarch.rpm
http://dl.fedoraproject.org/pub/fedo...c17.noarch.rpm
4) rpm -Uvh lohit-tamil-fonts-2.5.0-2.fc17.noarch.rpm
http://dl.fedoraproject.org/pub/fedo...c17.noarch.rpm

Restart e.g. 'Libre Office Writer' and the tamil fonts are present.

.

To find a Tamil fonts, go to
http://www.unifont.org/fontguide/
http://www.wazu.jp/gallery/Fonts_Tamil.html

You will probably get the fonts in a zip archive, not as an rpm package. Create a folder .fonts in your home directory (remember the dot in front!) Then click on the font package and tell the archive manager to extract into ~/.fonts. Your new font will be available in the next program you start.

To set up OpenOffice (or LibreOffice), click on Tools - Options. Choose the entry Language settings - Languages. Tick the box "Enabled for complex text layout" and then select Tamil as the default from the CTL list.