Used my new Canon 400D tonight for the first time tonight in astrophotography. Was aiming to image in particular the International Space Station, which I did......although it's very out of focus

I was using the 18-55mm lens, zoomed in a bit, and I took a 13 second exposure at F5.0,
this (
324kb) was the result
Later, I did a 1min31second exposure of the Achernar region and got
this result (
418kb) with the minimum amount of zoom (looks okay to me..)
All the time I was set to manual focus, but clearly I'm unfamiliar with how to focus the camera when I'm zoomed in on stars, can someone help me with this?
If it weren't for the focus aspect, I think the ISS image would have come out quite nicely