Raileurope is an American web site which (from what I hear) charges a huge premium for the convenience of letting you book European rail tickets with someone your side of the Atlantic rather than ours.

All European train companies have their own web sites, most of them have timetable tools, many of them have booking tools. It's just a case of finding them... (Somewhere out there someone has probably put up a web site with links to all of them, again it's just a case of finding it!)

There is a Europe-wide timetable tool at www.bahn.de (which is the web site of the German national railway company). The English version is here and the timetable tool is on the left-hand side of the screen.

This is a first step... once you've worked out some connections you will then want to find the national rail companies of the countries concerned to see if you can book online. It's probably easiest to type a few key words into a search engine (unless someone else on here comes up with the links!)

You don't need to book European rail travel months ahead - on shorter journeys people will generally just buy their tickets five minutes before departure and just hop on the train and find a seat. On longer journeys it's advisable to prebook (you will probably want the convenience of a reserved seat), but again it's not something you need to do months ahead - most Europeans don't. If you're travelling first class there isn't really any need for a reserved seat, unless you're travelling on one of the very few routes where reserved seats are mandatory. The timetable at bahn.de will tell you if you need to reserve a seat.