What should I do if I miss the obligatory prayers due to being at college all day?

It is obligatory to maintain the performance of prayers at their prescribed times, and studying is not a legitimate excuse for delaying prayer beyond its time. If one has delayed one or more prayers until their time has elapsed, then it is obligatory to repent to Allah by feeling remorse and vowing not to repeat the act, and one must make up those missed prayers in their proper order.