Getting Problem When connecting in sql server 2005

hi i have installed sql server 2005 and when i am going to open and connect it is showing this error i don't know why it is happening can any one help me .

Canonot Connect to SQLExpress

Additional information

an error ha occured while establishing a connection to the server, when connection to sql server 2005, this failure may be caused the fact that under the default setting sql server dies not allow remote connection,(provide:Name pipes, error 40-could not open coneection to sql server)(Microsfot Sql Server, error, 1231)