I received mail saying i had won money in lottery,UK,i have to pay courier? They said they are willing to help with installment from me to the courier.It had a yahoo emblem on it.The courier contacted me with details

You don't get anything for nothing, it's a scam do not answer do not give personal information.The following sites give more information.
www.scambusters-419.co.uk
www.truthorfiction.com
.Also If you go to the following link you will get some info on ID theft www.identity-theft.org.uk the iinternet is safe enough if you are careful but please answer nothing that you are doubtful about.Good Luck and be careful