First year, not doing so well

Just started my first year of University its been a little crazy. I have 5 courses currently and my university requires all students to maintain a 2.0GPA if we do not want academic warnings, etc. Anyways I have 5 courses 4 of which a mid-term was required, I just received my mid term marks and I didn't do so well. 2 of them I failed, one with a 45% and the other with 15% fortunately though, I aced the other two. My current marks are as follows - post midterm:
Course1: 92%
Course2: 62%
Course3: 78%
Course4: 84%
Course5: Got a 15 on the midterm so I dont even know what the fuck....
As you can see all my marks are all over the place. The course that I got a 15% for on the mid-term was totally split, half the class failed, the other half aced it, there wasn't an in-between (I was pretty confident going in to that exam to be honest).The teacher did say that if marks started to improve as the class went on the mid-term would not be weighted as much, so this mid-term wont prevent you from getting an A in the course if serious improvements are shown. The other course that I have a 62% in, is Math, which I have never taken an interest in or liked. Anyways, what can I do in regards to my marks, should I be worried? Any tips from people who have been in this situation? Would be good to see what people think, thanks.