General travel information can be found here.
When arriving at the airport (Frankfurt for most of you), take the train to Karlsruhe main station.
This link ( www.bahn.de/p_en/view/index.shtml ) provides information about the train connections and you can buy tickets there. Vending machines and counters are available at the airport station as well.
The hotels in Karlsruhe are in walking distance (more or less) from the main station, but it is probably best to take a taxi.
For entering the Campus, there is no security clearance necessary, but you will need to bring your passport or ID card. Don't forget it!