aijazzz ,
Sorry for the delayed response.
If you are trying to install plugins, and if you are behind a firewall, you will have to set up proxy here – Go to Window > Preferences > General > Network connections and then add the plugins via Myeclipse Configuration Center > Software tab.
Alternatively you can download the plugins and add them via [MyEclipse installation dir]/dropins . Take a look at this link for the format on dropins :
http://help.eclipse.org/indigo/index.jsp?topic=%2Forg.eclipse.platform.doc.isv%2Freference%2Fmisc%2Fp2_dropins_format.html
Let us know how this works for you.