As for your comment above on the use of the accusative and dative in the previous post/rant ( ), that depends on the situation. There is a list of prepositions of which 'auf' is one which take the accusative with movement towards and dative without movement towards. Example (using 'in' which is another one):
'Ich gehe in die Stadt' = I'm going into town [movement towards the town]
'Ich gehe in der Stadt' = I am walking about in the town. [You're already in town so no movement toward hence dative case needed. This is not a very idiomatic sentence in German but a lot of people are taught this rule simply as "Acc with movement and Dat without" which isn't true - there is movement in the 'gehen' in this sentence but it still takes the dative].
Beyond that there are numerous standard phrases which are similar to English phrasal verbs where the preposition takes a fixed case which may not follow the standard preposition-case rules and you just have to learn those.
I think German is a tough language to start to learn, but once you have a certain level of competence, it's much easier to get very good at than English is - there are just so many unfathomable exceptions to English grammar and usage - I'm glad I learned German as a second language and not English anyway!
Just my £0.02 anyway...