You cannot change the kerning from the glyph edit window — only see it’s effect. For adjusting the spacing it would be best to uncheck that checkbox (not as illustrated, though it didn’t matter for that font as it had no kerning pairs). To adjust the left side-bearing, select the entire glyph and move it to the right. To adjust the right side-bearing, drag the right side-bearing line with the mouse.
However, since you purchased the Pro version, use the Autometrics feature and see if you are satisfied with the results that it produces. To see several glyphs together, use the Preview Toolbar.
The screen shots in this thread were produced using the Preview Toolbar after running Optical Metrics.
The amount of white space can be set in the Autokern dialogue. I forget what the default is (maybe 350), but by setting the value to, say, 350 funits you will get fewer pairs and more space between them than if you set the value to 150, which would probably result in too many pairs and excessively tight kerning.
