Need a polynomial time reduction from 3SAT to INDEPENDENT-SET In order to show that a problem is NP hard one must provide a reduction from a known NP hard problem to this problem.
My question is how to reduce 3SAT to INDEPENDENT-SET?

3SAT is a satisfiable 3 literals in a clause Boolean conjunctive normal formula.
INDEPENDENT-SET is a set of vertices in a graph, no two of which are adjacent.
I do know how to reduce 3SAT to a Clique, would that help?
The simplest is to reduce Clique to Independent Set using the complement graph, as discussed in the comments.

Alternatively, you can construct a graph to directly reduce 3SAT to Independent Set using "gadgets". One possible start is to do the following: for each clause, construct one node for each of the three variables in the clause. Now, we want to place edges such that:


No two variables in the same clause can be members of the same independent set.
No two variables which are the negations of each other can be members of the same independent set.


If you can accomplish this, then for a boolean formula with $m$ clauses, there is an independent set of size $m$ in your constructed graph if and only if the boolean formula is satisfiable, thus giving the desired reduction.