what are some of edx or courses i can do in first year engineering ?
If you want to know about the best EDX courses available for the first year engineering students then please check out this official blog of edx:
https://blog.edx.org/10-most-popular-courses-edx-courses-in-2016
But personally I would suggest that you should take cs50 introduction to computer science course this is one of the best course that is available on the edx platform.