GRE

Though the GRE score could have been better, try applying to the universities. The other score are good.

You can get IELTS certificate by writing the IELTS exam, any other methods of securing the certificate would result in getting permanently banned from applying for any visa and possible criminal case.

USA is a hub of STEM programs, thus there are ample of universities that will offer you Computer Science courses. Universities usually have specific scores that they need in a particular section in the GRE exam. I personally visited Edwise for counseling and they gave me a good idea of the scores I would require. You could visit them.

You can check the individual requirements such as GRE TOEFL etc. On the links itself. https://studyabroad.shiksha.com/ms-in-abroad-dc11509
Narrow down your choice based on your budget, university admission requirements, your profile, location and climate preference etc. In terms of post study work options Australia and Canada are better.