Ok, so I didn’t do so great freshman year of high school, and now (including the first half of my sophomore year) my gpa is a 3.188 
If I get a 4.0 the second half of my sophomore year, junior year, and beginning of senior year. How much can I improve my gpa?
What changes are you going to make in order to raise the GPA? Are you capable of a 4.0 but not working hard enough, or are you by nature a B student - there is nothing wrong with B students if that is working up to the best of their abilities? I have a kid who earned B’s all through high school and college, and is now well respected in her field.
You need to do the math to figure out what is the most you can achieve for your GPA. For an unweighted GPA, you need your GPA’s for the end of each semester. Add those two totals together, along with your dream of 4.0’s for the next five semesters, and then divide by 8 (two semesters a year).
Some colleges do not count freshman grades, and many colleges look at “upward trend” in high school as a positive thing. And you can get into many colleges with a B average.
try google, type in college gpa calculator and enter scenarios to your heart’s content
For example:
http://gpacalculator.net/college-gpa-calculator/
It’s just possible your time would be better invested in STUDYING.