If you want to take admission in B.E/B.Tech you have to appear for engineering entrance like JEE (Main+Advanced). You can appear in this exam to take admission in IITs/NITs/IIITs and GFTIs. In order to be eligible for these colleges you should have 75% marks in your board exam or you should be in top 20 percentile for general category. 

For SC/ST it is 65% marks. 

To take admission in top private colleges you can appear in BITSAT, VITEEE, SRMJEE, Amrita and Manipal.

If you want to take admission in your state level government colleges you can go for your state entrance exam.

If you want to persue engineering make sure you take admission in top colleges to get good placements. There is lot of competiton to get into top colleges make sure you prepare for the entrance exam accordingly.

Good luck!!