gpg steps

export public key to asc
gpg -a --export FD9C1B26  > jfiq.pub


sign file/get pk
gpg -s segc-tarefa02.txt

sign file to asc format/get pk
gpg --clearsign segc-tarefa02.txt

add public key
gpg --import mo639_1s2012.pub

encrypt file/get uid
gpg -e -a segc-tarefa02.txt

References:

http://www.guiafoca.org/cgs/guia/avancado/ch-d-cripto.html

http://eriberto.pro.br/wiki/index.php?title=Usando_o_GnuPG

http://www.gnupg.org/gph/en/manual/x135.html