I would like to use an supercomputer to run my big data project to test it speed. I google the service & see that only this is available for free but it closed last year? Could anybody with experience in using supercomputer know to get access to this kind of hardware?
The answer will depend on where you are, who your funding is from, and what you mean by "a supercomputer".
Various countries, research councils, etc., let you apply for computer time if you are eligible. Some universities have their own in-house systems too.
But also, the major cloud providers - Amazon, Microsoft, Google (?) - will let you rent computing resources. This may be suitable for your needs.
What is your location and funding availability? Typically, one can get some time share on national scientific supercomputers through grants. You might use local clusters of your lab or university for testing and slower, but cheaper and easier available resource.
An alternative are clouds, e.g. the one from Amazon. It is quite cheap in processing time, as compared to commercial offers. It is also readily available. So, if you want a quick test and have money (in contrast to political influence or grants), it might be the faster way.
But generally, there are grids, there are cloud services (that are the same, but somewhat different), and there are the classical supercomputers (still grids, but own hardware, faster interconnections, etc.) While the principles are quite similar, you might need person-months to tune your application to the specific platform. Assuming, you want to squeeze maximal performance, of course.
A possible alternative might be GPU computing. If your task maps well to grid, it might map well to CUDA or OpenCL. Again, there are months of development to get it right, but probably lower entrance costs.