Well if you made tilemap, just increase its X and Y sizes, meaning you add more tiles per row and column and you get bigger map.
The view is pretty complicated for starters to get i agree, i had problems myself, but if you read the tutorial on how to use it and read thru the documentation you will figure it out easily.
What you probably want to make is a static position tilemap meaning it doesn't actually move. You want to move view around, something you probably know as camera.
To sumarize the game loop:
if User holds D, move units x position 10 pixels to right.
if User holds A...
CameraView.setCenter(Unit);
RenderWindow.setView(CameraView);//After this call, everything will be drawn with offsets of the view, you dont really to know those. meaning view left up corner can be x=213,y=512 that means if unit is at x=300,y=700 it will be on screen shown at x=87,y=188 if drawn with this view set on
Draw map;
Draw Units;
RenderWindow.setView(renderWindow.getDefaultView());//If you want to draw interface, set view to default so left up corner is x=0,y=0
Draw Interface;
//If you draw unit now, and its at x=300,y=700, depending on you screen size it will probably be off screen and not visible