Can i connect rails on Connie Express to an existing Train Station

The simplest way to go about it is with autocomplete (which you'll find in the ride edit tools in the bottom centre of screen). You might need to back up a bit to give the track room to connect up, but play around with it and it works well, you'll find it. You can re-edit the track afterwards .. to drag it to a new shape if you want to.

Have you started a 'new' conne express ride by the way? Suggest you don't (though it sounds like you might have) as you can add multiple stations in a single track ride, and I'm pretty not sure you can join two different rides together.