From Voice of the Martyrs. For some background on the case of Asia Bibi, sentenced to death under Pakistan's infamous blasphemy laws for witnessing to her Muslim neighbors, see Monday's post.
From the link above, click on "Petition Official" on the right, then "President and Chief Executive," again on the right. This will open an email addressed to Pakistan's President. You will have to put your request in your own words.
You may want to reference the words of Article 18 of the United Nations' Universal Declaration of Human Rights, which states that
"Everyone has the right to freedom of thought, conscience and religion; this right includes freedom to change his religion or belief, and freedom, either alone or in community with others and in public or private, to manifest his religion or belief in teaching, practice, worship and observance."