[dba-SQLServer] Logging in to remote instance of SQL Server Express

I have installed SQL Server Express on a client's computer and configured it
for remote access.  I'd like to log in using SS Management Studio from my
computer.  I can't find any documentation on the exact format of the login.
I've tried some variations without success, but I don't know if I'm logging
in correctly or I have some other connection problems.

If the client ip address is 111.222.333.444 and the server name on the
client is DAVE\SQLEXPRESS, what should I be entering into the 'Server Name'
box of the SSMS 'Connect to Server' dialog box?

Thanks,

Doug Steele