Getting to know Photoshop
First things first:
You need to get to know the main tools I will be referring to throughout the tutorial. The key ones I have highlighted to the left (and labeled for you.)
3) Set the image mode to Grayscale via the menu under Image > Mode> Grayscale (Set the Ratio to 1)
4) Now, using the exact same menu, then set it to RGB Color. You cannot go from Bitmap to RGB directly, sorry.
5) Crop the image using the CROP tool by outlining the image until the drawing either barely touches the edges or meets it at a point. This gets rid of negative space and pixel borders that you do not want/need.
6) Double click on the Layer "Background" in the Layers Menu. If you do not see this menu, you can show the layers palatte by going to Window > Show Layers on the main menu bar.
Name the layer "Line Drawing" so you don't get it mixed up with the other layers.