Step one take your mold out and make sure it is clean. Mix the two different halves of liquid resin in a separate cup. Pour it slowly in to the mold. It helps to use a tooth pick to stir it around and fill all the corners and small bits
Step three once your model is in shape (note the green patch where an air bubble was) You can get into fine details. I like to add "gun sponsions" or small swivel guns to the superstructure. These small details don't cast well so I add them after that step. I use a small drill to drill holes where the guns will go. It is possible to go further and cast separate components such as large turrets or superstructures and add these to your ship (This mould be ideal for a monitor). This lends detail and complexity to the design but can be very tricky to get right.
You can see here the holes drilled into the side of the superstructure.
Lastly cut small pieces of paper clips and fit them in as guns, the same can be done for masts. Now you can paint and base and you are ready to go. As a final warning I will say not all castings will be usable many of mine have failed and your first few might be failures but keep going you will get it in time.