Not able to install TestNG

Hi,

I am using Eclipse Luna 4.4.2. When I try to install TestNG through "Install New Software", getting an error "Could not find http://beust.com/eclipse". I tried with Eclipse Mars 4.5.2 and getting the same kind of issue.

I tried to Install through "Eclipse Marketplace" but when I try to open "Eclipse Marketplace", getting an error message "Can not open Eclipse Marketplace".

Can any one please update me what could be the issue here?
Screenshots attached.

[b:1wu9jkms]Note[/b:1wu9jkms]: I don't have admin right on the machine. Should I need admin right to install the TtesNG plugin?