We counted to 49 in ASL, let's keep going!
To do the sign for 50, make the hand sign for 5, with all your fingers out, palm facing away from you.
Then close your fingers together all pointed forward away from you, for zero.
For 51 through 59, just do the sign for 5, and then the sign for the number 1-9.
Here is a helpful video to show how these signs are done.
ASL Numbers 30-100 in Sign Language - My Smart Hands

(from: wikipedia - american sign language)
Italian: cinquanta, cinquantuno, cinquanta due, cinquanta tre, cinquantaquattro, cinquantacinque, cinquantasei, cinquantasette, cinquantotto, cinquantanove
German: fünfzig, einundfünfzig, zweiundfünfzig, dreiundfünfzig, vierundfünfzig, fünfundfünfzig, sechsundfünfzig, siebenundfünfzig, achtundfünfzig, neunundfünfzig
Spanish: cincuenta, cincuenta y uno, cincuenta y dos, cincuenta y tres, cincuenta y cuatro, cincuenta y cinco, cincuenta y seis, cincuenta y siete, cincuenta y ocho, cincuenta y nueve
French: cinquante, cinquante et un, cinquante-deux, cinquante-trois, cinquante-quatre, cinquante-cinq, cinquante-six, cinquante-sept, cinquante-huit, cinquante-deux