Hello Aspirant, To get admission in IIT Kharagpur, you need to first clear JEE Main first with ranks upto 2,24,000. Then you will have to appear in JEE Advanced and after qualifying in this exam, you will get a seat in IIT Kharagpur. 

The cutoff of the computer science for ST category is that your rank must lie between 2 to 40.

I hope this will help you.