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If we apply time expansion formula of theory of relativity on Light to detemine how long has it travelled according to our time than what'll I get ?
I cant figure it out

as much as i know, time doesn't exist for light.
what do you mean by "our time" ?

Yeah, your question is not clear to me. If you mean in a certain frame how much time has elapsed for light to travel a distance $d$ then it is simply $t=d/c$.
Also light's frame is not quite well defined, because if light is moving at speed $c$ with respect to me, then that will mean I am moving with speed $c$ with respect to light's frame, but nothing can actually attain that speed.

I meant in the reference frame where I'm stable and light is moving at C.
Well, we determine the travel time of moving thing on account of his reference frame by dividing the time in our reference frame with $(1-\frac{V^2}{C^2})^{\frac {1}{2}}$.
Hence $V=C$ for light we get $0$ as denominator as this is my problem.

you are right. That's why there is not such thing as "light's reference frame". It does not exist. Reference frames are only defined for things moving slower than light.