Firstly, let me welcome you to the Guild, The Mappiest Place on the Web.

Secondly, we have a great store of tutorials on making maps using all sorts of programs, as well as a few with Pen and Paper, that range from beginner all the way up to "OH my god I will never be able to do that in a million years". It is surprising how fast those "million years" can go by with but a little effort and perseverance if you give some of those tuts a go. If you do give it a go I would suggest that you post up a WIP (Work In Progress) in the appropriate forum in order to get some helpful comments and critique. Don't be shy about it either because we are a friendly bunch and the C&C will be of an encouraging nature.

Thirdly, there are many authors here at the Guild who came here for the exact same reason as you did, and there are quite a few threads asking the same questions as you. You might need to look through the Member Intro, General Discussion and How Do I? forums to find them, but I think they are worth the effort to find and read.

Now, I am not a writer, but I would think that you have a rough (maybe very rough) idea of what the layout of that world may be. Even if it is just this nation is on the coast, this one is to the north and there are some sort of mountains here, here and there, and the border of these nations runs along a river. Just that is enough to start a map. Start with a blank piece of paper and a pencil and draw a vertical squiggle about a third of that page in from one of the edges and call that the coast (at this stage nothing is final in the least) and in the middle and on the larger side of the "coast" draw that coastal nation by starting at the coast and drawing another squiggle that connects back to the coast somewhere. Now place the second nation to the north of that. Now place a few oblongs for the rough placement of the mountains and darken the boarder of the two nations for river between them and you now have a very basic sketch of the land and can develop that as you write your story. The same process works if you are writing about the whole world, but I suggest you only apply details to things that need it for the story or as background. If locations are only mentioned once or twice (as in a character is from Chibigaboo and Chibigaboo is also mentioned as being many seasons travel to the west though great impassable deserts but no characters actually go there) then they can be placed abstractly on the sketch (as in the name of the place and an arrow on the appropriate edge of the paper. Something like this should be enough to keep all of your ducks in a row, and will develop into more of a map as you add details to your story. Add or erase details (like defining the coast more and adding forests, towns or rivers) as you go and what was rough to start can turn into something that fits what is in your head. Having this visual aid will also help sort out inconsistencies that might crop up.

If you need help in understanding things like where/or how mountains are placed, we have stuff on that too. In any case, the WIP threads are your friends as you can pick up all kinds of ideas just by reading through them.