I'm used to something = it is not new or strange for me. Let's see the following examples.
Do not confuse I am used to doing with I used to do. They are different in structure and in meaning. to be used to + ing means isn't strange for me.
I used to do something means that I did something regularly in the past. You can 't use this structure for the present. Let's see the following examples.
In this exercise you have to complete sentences with to be used to doing or used to do.