Your hand was something rather like
 
S    xxx
H    ??xx
D    QJ
C    AJxx
 
The bidding was        Me        You
                                1S        2C
                                2D        2H
                                4S        pass
 
My bidding for the first two rounds shows at least 5 spades and 4 diamonds.
You have at least 4 clubs and an unknown number of hearts.
The 2H is "fourth suit forcing", so the ?? were probably honours.  You want more information.
By jumping to game, I am strong and forcing you to choose between my two suits at a high level.  My shape must be 7 6 0 0 or 6 6 1 0 to be making such a drastic bid.
Looking at your hand you can now start tgo get excited as we have a double fit.
We have at least 9 spades and 8 diamonds, where your QJ are gold plated.
Given my opening bid I have 13 ( and probably more given my later jump) high card points to which you can add 5 for the void and 3 for the singleton - 21 in all.
Suppose you have 10 high card points.  Add 1 for the doubleton and 1 for the extra length in spades - 12 in all.  21 + 12 = 33 which is enough for slam!
Outside of my suits we may or may not have one loser depending on whether I have a heart or not.
You can bid 4NT to ask for aces, hoping that I have 2 and reply 5H, in which case we have only one loser off the top, and 6H should be bid.  If I have fewer than 2 aces you can sign off in 5H.
 
Maybe your second bid should have been 2S or 3S, as we have a fit in spades.
NB. Before I bid 2D you did not know about the fit as I could have had 4 3 3 3 and bid 2NT.
 
It was a very hard hand with some interesting features.
I should actually have jumped to 4D, showing 6 6 1 0, and not 4S, but I did not want to be dropped in a non-game contract!!
 
P