Assuming that you want to create a regular font, and not a white font on a solid black background.
- Open the image in PhotoShop (or IrfanView)
- Invert the image to black on white
- Select one number and copy it to the clipboard
- Start a new font
- Open the appropriate number in the glyph edit window
- Delete any contours that are there already
- Paste the bitmap from the clipboard
- Adjust for position on the baseline and adjust the side-bearings. (Don’t resize it)
- Repeat
- Resize all glyphs using the Transform Wizard (Pro version) or the Transform Toolbar (Home version)
Read the topics Scanning an Entire Alphabet and Importing Images the Right Way.