Colleges in Himachal Pradesh

Civil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including works like roads, bridges, canals, dams, and buildings. Civil engineers design, build, supervise, operate, and maintain construction projects and systems in the public and private sector, including roads, buildings, airports, tunnels, dams, bridges, and systems for water supply and sewage treatment. Many civil engineers work in design, construction, research, and education. Civil engineering is an age old profession and with Government of India focus on infrastructure scope and opportunities for Civil Engineer will be very high for next few years.
You are advised to appear in JEE Mains and JEE Advanced to seek admission in IIT Mandi for B.Tech civil engineering.

I am going to assume that you belong to the general category. As for the home state quota, if you belong to HP, you can get admission into CSE, ECE, Mechanical, EEE, Civil and Chemical branches at NIT Hamirpur, but can not get admission into PEC. If you belong to any other state, you can get admission into Civil and Chemical at NIT Hamirpur, however if you belong to Chandigarh, you can get admission into Aerospace, Civil, Electrical, Metallurgical, Mechanical and Production & Industrial Engineering at PEC. If you do not belong to Chandigarh, you can still get admission into all those branches, but by a small margin for the Mechanical Engineering branch.