you can not sex them until they begin to reach maturity - - about 6-8 months of age.
for two frogs, you NEED a 20 gallon tank....hope you are prepared! these frogs get quite big - - their body size (NOT including legs - - ) males 3-4.5" and females 5-over 6"
no fish tank mates
no freeze dried food - - best if fed reptomin / turtle sticks
no gravel substrate - -
actually, just check the link in my signature for care info
or if you have questions you can post them here and I will answer them as you ask them!