I have a feeling you cannot file online if you are outside the US. I seem to recall that this was the case a couple of years ago, but I'm not sure if they have changed this now or not.
In the case of your spouse not having a SSN, you would usually put that he is a NRA (Non Resident Alien) in the box where it ask for his SSN - but if the online form will not let you do this, you may need to file the paper forms instead (or another option, I think, is to get him a ITIN number, but that might be too much of a hassle, especially if he did not live in the US last year and has no reason to file taxes himself).