So, you start off as a major-league slacker, ("I did a lot of slacking and did not learn the study methods required to survive in college") then do a bit of studying while remaining a fairly hard core slacker ("I really need to change the way I study and improve in these classes which should be simple."), and blame your few remaining low grades on "tough graders." Well, I know I'd be knocking down your door trying to give you a scholarship.
Try revising your essay to put yourself in a better light. Explain that you got very good marks in high school without having to do much work. When you got to college, you found the expectations were much higher, which caused your marks to drop. You then rose to the challenge, studying hard, dedicating yourself to your academic career. This resulted in a restoration of your marks to mostly As, though not enough to pull your GPA back up over 3.25 when your lower first semester marks are included in the average, though you came very close, with a 3.18.
The above is the general sense of what you should say. However, you should say it by including specific examples of courses you took and study practices you implemented.
Sean, EssayForum.com