TOPIC:

I want to create a rule,


Here is what i made, Is this correct or what modification needed

Name=Free Shipping; 50<= Amount; 0
Name=AllWeight; 3>=Weight; Shipping=10

There are several changes needed to your approach:

1) The maximum weight of all items in the cart is available in the MaximumWeight variable. the Weight variable gives the total weight of the order.

2) The condition "3>=Weight" means: if the total weight of he order is smaller or equal to 3. You rather want "3<=MaximumWeight" (i.e. the largest weight of any of the articles in the order is larger or equal to 3).

3) If you place the free shipping first, the second rule will NEVER be even checked for orders above 50$. So you need to either place the weight-based rule first or add an extra condition for the maximum weight.

I would use this:
You probably also want a rule for standard shipping costs...

Best regards,
Reinhold