There's a pretty big difference between how Marvel's Ghost is represented in the comics versus how the character appears in the Ant-Man films. Most notably, in the comics, Ghost is a man.
Originally, he was an Iron Man villain with an ambiguous backstory who worked as a mercenary and liked to crusade against corporate greed. His motivations are pretty abstract, citing large concepts like chaos or anarchy as his general goals.
He acquired his powers after a series of accidents led him to change some things around in his body; lucky for him, he's a genius and was able to invent a suit that gave him the power to turn himself or objects he comes in contact with, invisible or intangible. He has invented other gadgets to help him out and he's also a pretty impressive hacker which comes in handy often.
As far as Ghost's MCU debut, hardcore fans were probably surprised that Ghost is a woman played by Hannah John-Kamen in this interpretation. The trailers suggest that she gets her powers from the quantum realm in the movies, and has some kind of a history with Dr. Pym and/or Dr. Bill Foster. The big question is, if Ghost can manipulate the quantum realm to get her powers, does that mean Pym can manipulate it to find Janet Van Dyne?
We're excited to see how all of this factors into the plot of Ant-Man and the Wasp, and maybe answers the question as to Ant-Man's absence from Infinity War. If you want more details about Ghost, check out the video above.