While progressing through the first level of the game - the Factory - you will come across a green exclamation point on the map in a small room. Attack the computer in this room and the doctor will tell you that you need to be stronger by upgrading. To do this you need to have at least one box of nuts in the top right corners which can be acquired by defeating enemies; press the menu button and select a weapon or Heart himself and 'purchase' any upgrade. After doing this, return to the computer you attacked and do so again. The doctor will then congratulate you and give you an item, along with this achievement.