For boys, the introductory line is:
יְשִׂימְךָ אֱלהיִם כְּאֶפְרַיְם וְכִמְנַשֶּׁה
Y’simcha Elohim k’Efrayim v’chi-Menasheh.
May you be like Ephraim and Menashe.
For girls, the introductory line is:
יְשִׂימֵךְ אֱלהיִם כְּשָׂרָה רִבְקָה רָחֵל וְלֵאָה
Y’simeich Elohim k’Sarah, k’Rivkah, k’Rachel, ooch’Leah.
May you be like Sarah, Rebecca, Rachel, and Leah.
The rest of the blessing is:
יְבָרֶכְךָ יְהוָה וְיִשְׁמְרֶךָ
Y’varechecha Adonai V’yish’m’recha.
May God bless you and guard you.
יָאֵר יְהוָה פָּנָיו אֵלֶיךָ וִיחֻנֶּךָּ
Ya’er Adonai panav eilecha vichuneka.
May God show you favor and be gracious to you.
יִשָּׂא יְהוָה פָּנָיו אֵלֶיךָ וְיָשֵׂם לְךָ שָׁלום
Yisa Adonai panav eilecha v’yasem l’cha shalom.
May God show you kindness and grant you peace.