Hola, yo soy/me llamo/[mi nombre es] "Cassie". Encantada de conocerte.
" " " " . Es un placer conocerte.
" " " " . Me alegro de conocerte.
" " " " . Mucho gusto.
Yo soy Cassie or Me llamo "Cassie" sound more relaxed and natural than "Es un placer conocerte". In the latter formula there is a bit of a clash between the formality of "Es un placer conocer" and the familiarity of "te". If you are meeting somebody to whom you want to express respect (because (s)he is older, a teacher, a prospective employer, etc.), then say: "Es un placer conocer-LE/LA" (masc./ fem.).