How to encode a message to MD5?
MD5, like most cryptographical algorithms, takes inputs which are strings of bytes (actually, bits, however we rarely need to hash an arbitrary bitstring).  So, yes, to hash a string with MD5, you need to convert that string into a series of bytes somehow.

As for how you do that, well, for a string like 'amrasobalatel', the most common transform is to take the ASCII encoding of that string; however there's no reason you couldn't use UTF-16 or EBCDIC...