never say that u r not good in studies......every body has untapped potential in them..u have to jus work hard and make a vision.....develop desire for the exam n u'll make it to good college.
now for studies first start from the basic level thats NCERT and then move on to higher level with this your prepration for boards and copetitive exams w'll move simoultaneously.
books that u can use.
1)arihant organic chemistry
2)arihant inorganic chemistry
3)krishna objective chemistry (only inorganic part)
4)p bahadhur for numericals
5)arihant physical chemistry
6) hc verma for physics
7) sanjeev gupta for physics
8)ml khanna for maths