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How did you attain a firm footing in your friend's life? Did you step on him, Sanjay?

As Rahul said, you have a dangling modifier.

Answer #2

Okay, Sanjay.

A dangling modifier occurs when you have a modifying phrase that is not adjacent to its subject (or where the subject is missing entirely). Let me give an example that somebody posted a couple of days ago.

While doing the laundry, the cat jumped onto the washer.  Who was doing the laundry? Because "the cat" immediately follows the introductory modifying phase, grammar tells us that the cat was doing the laundry. But that does not make sense. The phrase "dangles" because the subject it is trying to modify is missing.

In your sentence, "I" immediately follows the introductory modifying phrase. So grammar tells us that "I have attained a firm footing in your life." That is why I asked if you stepped on your friend.

You can correct this problem by making it clear who has attained a firm footing. "Now that you have attained a firm footing in your life, I am sure ..." "Having attained a firm footing in your life, you surely will go on to ..."

I found a problem related to dagling modifiers:

Having attained the firm footing in your life, I am sure you will go very far on the path of achivements.