Hello Milan,
You can do the following to access your ASA from internet:
you need a public/private keypair:
asa(config)# crypto key generate rsa general-keys modulus 2048
a username:
asa(config)# username testuser password testpass
and the system should know where your useraccounts are:
asa(config)# aaa authentication ssh console LOCAL
permit ssh on the outside for everyone
asa(config)# ssh 0 0 outside
Edit: And only allowing SSHv2:
asa(config)# ssh version 2
