Hmm well I seem to be struck for time so I will try and give a little tutorial (also I only know how to make provinces, not change the shape of land or add islands of anything)
remember that it is best to copy and paste a new WWM file as if it doesn't work, you can always delete it and still be able to play on your original WWM.
Firstly open up the provinces file in the map folder. You should open it in paint.NET or Photoshop (I use Paint.NET).
You will see that the world is upside down so you will have to vertically flip it.
Then zoom into where you want to edit and pick a colour
You should pick a colour with the colour picker and then change the R, G, B (red green and blue) numbers by like one, this way it will be unlikely to have a colour with the same RGB, also something very important is you don't want the same colour twice, you can have something with a RGB of 201,38,0 but it is ok to have another one with 201,38,1 as long as they are not exactly the same.
then draw on the provinces with these new provinces, try not to replace a province completely and have at least part of it left, if you want to change the name, do so in the localisation.
Next once you have finished the drawing, open the definition file which is also in the map folder.
It should say things like province
this is the province number, followed by the red, green and blue codes.
so for example you wanted to add Porbandar you would put:
I chose province number 2091 because there are 2090 provinces already in the game, the previous one was Elba with the code:
So as you add these provinces, you will have to make the numbers go up, but try not to leave gaps as I don't know what happens.
If you are adding all these provinces you will need to make the mod recognise more provinces, so open up the default file in the maps folder with something like notepad, you will see at the top:
, increase this to 1 more than the number of provinces you have added.
max_provinces = 2091
Then once you have done all of this, open up the continents file and look for India, it should look like this:
All you then have to do is add in the province number you have. Easy!
503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523
524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544
545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565
566 567 568 569 570 571 572 573 574 575 576 577 578
Then you open the regions file and do the same.
Now it is time to leave the maps folder and go to the localisation folder. This is the file with all the names of stuff, so try not to touch anything other than what you are doing or you could cause chaos.
In this folder look for a file called newprovs (this only applies to the WWM).
This is the file with all the new provinces in.
It should say stuff like:
You then scroll down to the bottom and add your provinces.
PROV1742;Vänern;Bassin de Tiki;Tiki-Becken;Basen Tiki;Cuenca de Tiki;Bacino di Tiki;Tiki medence;Pánev Tiki;;;;;;x
PROV1744;Gulf of Bothnia;Golfe de Bothnie;Golf von Bothnien;Zatoka Botnicka;Golfo de Botnia;Golfo di Botnia;Bothnia öböl;Bothnický záliv;;;;;;x
PROV1745;Ålands Hav;Mer d'Aland;Ålands Hav;Morze Alandzkie;Mar de Åland;Mare di Aland;Ålands Hav;Ålands Hav;;;;;;x
It is important to add the same amount of names as the rest of the file and the same amount of the ';;;;;;x' things otherwise it will crash the game or cause problems with all the names.
Once you have added all of the provinces corresponding to the rest of the files, it is time to go to the history folder and then provinces and you should see all of the provinces with all of their numbers and names.
What I do is open up a file which is similar and copy and past it except changing the name of the file e.g. 515 - kathiawar
change that to 2091 - porbandar and then open it.
Change it to how you want and then do it with the rest of them and you have finished and it should be in the game, if it crashes, try to figure out what you could have done wrong, usually to start with I would only add one province and see if it works and if it does, then do the rest.
#2091 - Porbandar
owner = GUJ
controller = GUJ
culture = gujarati
religion = hinduism
capital = "Porbandar"
trade_goods = cotton
hre = no
base_tax = 1
manpower = 2
citysize = 4311
add_core = GUJ
fort1 = yes
discovered_by = indian
discovered_by = muslim
For the positions of cities I would suggest using positions editor by MichaelM. It makes things like this much easier.
Hoped that helped!