For boys, the introductory line is:

May you be like Ephraim and Menashe.
יְשִׂימְךָ אֱלהיִם כְּאֶפְרַיְם וְכִמְנַשֶּׁה.

For girls, the introductory line is:

May you be like Sarah, Rebecca, Rachel, and Leah. 
יְשִׂימֵךְ אֱלהיִם כְּשָׂרָה רִבְקָה רָחֵל וְלֵאָה. 

For both boys and girls, the rest of the blessing is:

May God bless you and guard you.
יְבָרֶכְךָ יְהוָה וְיִשְׁמְרֶךָ 
May God show you favor and be gracious to you.
יָאֵר יְהוָה פָּנָיו  אֵלֶיךָ וִיחֻנֶּךָּ 

May God show you kindness and grant you peace.
יִשָּׂא יְהוָה פָּנָיו אֵלֶיךָ וְיָשֵׂם לְךָ שָׁלום


haggadah Section: Introduction