Gimp Basic Edits
Click on the crop tool (looks like a razor blade)
Draw a box around what you want to keep
Click on the outside edge of the box to crop
SCALE AN IMAGE (SMALLER/BIGGER)
Go to Image, then choose Scale Image
Change the dropdown from PX to Percent
Enter in a percentage to try in the Width & Height and hit Scale
If it is still too big or too small, undo your changes and try it again
LEVELS & HISTOGRAM
Choose Colors and then Levels ...
Move the black and white sliders to the edge of the histogram and adjust the middle slider until it looks right. Click Ok when finished.
SAVE VS EXPORT
If you are still editing your picture choose File, then Save As …
Make sure you give it a good name, tell it where to save. It will be a .xcf file.
When you are finished editing, you need to export your file. Go to File, then choose Export As …
Click on the plus sign by Select File Type
Select the right file type (give it a good name, tell it where to save) and choose Export
Leave the settings on the next box and hit Export again