Hamburg to Amsterdam

Hi i am travelling to amsterdam from Hamburg on the 4th of july.....would anybody be able to suggest the best way to do this? i was thinking maybe get the train, but should i book in advance or can i just pay when i get there?
many thanks

Ever so easy....
Hamburg - Amsterdam direct on the train. Sometimes with a change in Den Haag (The Hague).
If booked in advance (Rail Europe will do a cheaper ticket if bought more than 14 days before departure), expect to pay about €35 one way.
If you want to buy a ticket on the day, there won't be a problem - but the cost will be quite a bit higher.
Also, consider an internal train to the D/NL border, getting off and walking across to the nearest station in Holland - then boarding another internal train to Amsterdam. It'll - for sure, work out cheaper than an international train doing the whole trip in one go.
Expect the whole journey to take between 4 to 6 hours.
Enjoy!!