Hey there,
First things first - great to have a new modder on board. Welcome!
I would suggest to get started - kitbashing up a small frigate-sized ship, and getting that in the game for a starting point.
You'll probably want to look up one of the ship-making programmes to aid you in getting it in the game - but also check out some of the structures of other mods to get an idea of the general 'data' requirements that are needed to support the ship existing in the game (and being able to be interacted with).
Good luck and let us know any specific issues you're having, but it's good (I think) to try and figure these things out yourself as - with familiarity - you'll then be much better equipped to add the sceond / third / fourth ship plus generally develop your mod in to whatever you want it to be.