My picasa web album is linked to my google plus account. My public url has a long string of unique numbers on it . My Question is how do we change the string of numbers to my gmail account username.

I have been searching for this this the whole day but couldnt find the option

currently its https://picasaweb.google.com/111293829763795395367 i want it to be like this https://picasaweb.google.com/mevinbabuc