All I have is the Spanish link, but it is easy to follow.

www.amnistiapornigeria.org   

( I have tried to make a blue clicky link but I don't think it has worked.. help ? )
www.amnistiapornigeria.org

Anyway, this page will ask you for your

nombre ( first name )
apellido ( family name )
provincia ( region / state )
pais ( country )

Click on accept and it will then ask for an email address which is optional.

It is easy to say that these things don't make any difference, but the email I received said that a similar capmaign HAD saved the life of a woman in a similar situation, and that it would appear that not enough people have signed this petition for them to take any notice in this case. That may be naïve, but it only takes a couple of minutes to sign and it's worth a try.

Meanwhile, if anyone has a good link in English that would be great.