They end that way because they are in "infinitivo", infinitive. It is the equivalent of saying "to x"
Eg.
Aprender - to learn
Vivir - to live
Encontrar - to find
The conjugation (-er, -ir or -ar) depends on each word, it is a matter of memorising them, I'm afraid.
Hope this helped :)
El viernes 9 a las 8:30 am ir pm
From a drink,intoxicant drink
