You want to sort a multidimensional array without using an existing sorting function? Then you need to select a sorting algorithm and write your own function for it.

An example: Selection sort - Wikipedia, the free encyclopedia

Don't even know what language you're coding in... That's a Java example at the Wiki, but could easily by converted to PHP, C++, Python, etc...

Certainly not the fastest or most efficient way to sort, but it's simple enough.