I am an undergraduate in my first quarter. I did very well in high school, but this first quarter kind of hit me hard workload-wise. I got one A-, two Cs, and a D+. Will these poor grades screw up my chances of getting into law school in the future?
A bit early to worry about law school. Take some time over break to figure out what went wrong, and how to fix it. If you did well in HS, what do you need to do to carry this over to college?
This is very doable; many many people have terrible first quarters/semesters in college and make the adjustments necessary to do better. You can too.
You have plenty of time to improve your GPA. The combination of GPA & LSAT are really by far the most significant factors in law school admission. If you can get your GPA over 3.0 and you can achieve a reasonably strong LSAT (say 160) you should have plenty of law school options. If you want to apply to top law schools you still have a chance but the more highly ranked the law school the higher your LSAT would need to be. It is probably not that unusual to have some poor grades during your first college semester. What happens next semester and for the balance of your undergraduate studies is what matters.