You can get placement through college campus or you can go to PSU through GATE.

If u get in a good college then u get placed through the college directly through college placement

There are number of opportunities that are available once you complete your engineering. You can also appear for the GATE exam as a number of PSUs hire on the basis of the GATE score. Colleges also have placement cells. Companies also hire directly from colleges. Moreover, there are a number of recruitment websites. You can post your resume there and appear for the job interviews. You can also check the career section of the companies which are there in your field as in the branch in which you have pursued your engineering. You can apply through the company websites also.