I started using circular knitting needles and I guess I can use them because I’m creating this large circle thingy…
I think it will fit me if I am to make a sweater or something out of it, but 'm not sure how to do anything…
I started knitting 2 months ago and kinda suck…
So I would be really thankful ifsomeone could provide me with some help as to how to finish this tube thigy and make it into a vest, tank top, or something simple with really simple instructions 
Thanks!
Hmm, well once it’s big enough I guess you could bind off to make a super simple tube top! If you wanted you could knit and sew on some straps for a tank. Did you cast on with the right number of stitches to make a top? If you weren’t planning on making a top to begin with, it is kind of unlikely that it will fit too well. 
I’m not sure you can just make a tube and then turn it into something else unless you are a super experienced knitter and even then I don’t know if it would work.
You might consider using a pattern next time. You will learn more about construction and following patterns. 
Knitting Pattern Central
Sorry I can’t help with your tube.