on the image to bitsy page, if you scroll down there are some instructions! I will try to explain more clearly here:
- in Bitsy, under the Tools dropdown, open the 'Game data' window and copy the game data to your clipboard
- make a backup!! you can click 'download game data' in the 'game data' window here and save a copy somewhere
- open Image to Bitsy
- under the 'game data' section, paste the game data into the text box
- under the 'image' section, click the file upload button and select the image you want (.jpeg and .png are best, but I think .gif and .bmp should work too)
- crop the image if you want, using the slider and dragging the image around
- under 'palette', select a palette (if you haven't added any palettes, there'll only be one to choose from)
- under 'preview', adjust the brightness if the image is too light or dark
- under 'output', check that everything looks good, enter a name for your room and click 'save to game data'
- under 'game data', copy the game data from the text box
- in Bitsy, paste your game data back into the 'game data' window text box
voilà! you should now have a new room in your Bitsy game...