Hey Guest! Ever feel like entering a Game Jam, but the time limit is always too much pressure? We get it... You lead a hectic life and dedicating 3 whole days to make a game just doesn't work for you! So, why not enter the GMC SLOW JAM? Take your time! Kick back and make your game over 4 months! Interested? Then just click here!
What is a "normal editor"? Maybe it's too normal and you need a "special editor".
Your image apparently does not have an alpha channel. Save it in a format that has an alpha channel, using software that supports saving alpha channels (read: Not MS Paint). An example of that would be Paint.NET, or GMS' own sprite editor.