Hi Avani,

After you qualify JEE Advanced, you will have to apply for JOSAA counseling. You will have to register first. You will be asked to fill choices on the basis of your preferences. And then a seat would be allotted to you on the basis of your rank. Then you will have to report to the reporting center to confirm your choice. You will have to choose amongst the three options ie either of Freeze, Float or Slide.

Freeze: It means you have been allotted a seat and you’ve accepted it and you don't wanna participate in the further rounds of counseling.

Float: It means you have been allotted a seat and you’ve accepted the seat but you want a better program (quite obvious) than what you’ve been allotted. In this case, once you are allotted a seat in the further rounds, you’ll lose the seat which was allotted previously. 

Slide: It again means you’ve been allotted a seat and you’ve accepted it but you seek for a different course in the same institute in which the previous programme was allotted. 

Open the link below for more details about steps:

https://engineering.careers360.com/articles/josaa-counselling

Below is the list off all JEE Advanced participating institutes:

https://engineering.careers360.com/articles/jee-advanced-participating-institutes

All the best

You can join 

Newer iits 

You can admit into 

Indian institute of space and technology 

Thiruvananthapuram

Also 

IISC Bangalore has admission through JEE advanced.

Rajiv Gandhi institute of petroleum.

Indian institute of chemical technology.

And even many private institutions.