hi,

see gate and ceed exam is not for you as you are in 11th , gate or ceed  exam can be attempted  by candidates who are already graduate or in final year of graduation in relevant discipline.

as you want to take admission in iits, you need to apply for uceed exam which is the undergraduate design entrance of iits, also you need to apply for jee main exam, which is the common entrance test of engineering, basis on jee main score candidates may appear in jee advance exam, which is the gate way entrance exam of admission in iits for btech courses.

hope it would help.