chocolate fudge not having harder or sticky consistency how to make a proper chocolate fudge, which is as shown in picture?
I followed a recipe shown online, where condensed milk and chocolate chips have put in Microwave oven for 3 mins; and after refrigerating; it was perfect fudge.

When I followed the same recipe; after refrigerating; it became so watery as a sweet chocolate sauce, Please help;
If condensed milk and chocolate chips are, basically, your only ingredients, make sure you are using sweetened condensed milk and not just evaporated milk.  The 5-minute fudge recipe has been a staple of bake sales and church socials for as long as I can remember and should work on a 3-minute microwave cycle. Some recipes mix the types of chips (milk chocolate + semi-sweet chocolate) - some recipes throw in a couple tablespoons of butter into the mix (Eagle Brand's recipe is more purist, though). But sweetened condensed milk and a LOT of chocolate chips should do the trick.

http://www.eaglebrand.com/recipes/details/?RecipeId=3968

The only other problem I can think of would be if you microwaved your chips alone first and they got so hot that the chocolate seized - or if you used some kind of chocolate flavored chips that were made from mystery materials.

I don't like to use the microwave to melt chocolate - ever.  For a recipe like this, I would melt the chocolate into the sweetened condensed milk over a double boiler or in a heavy saucepan over low heat - sometimes slow and steady wins the race.