alright that works and you got the basics but it has two things in it that I would change, it can be way easier than your attempt.
the first one is just to save some time and make things a little nicer.

Instead oj using a textfile to store the map youse a binary file. The textfile has the advantage that you don't need to program a map editor to create a map, but as easily as you can use notepad to create the map anyone will be able to alter the map. And it's also a waste of diskspace... (oh well) and it's also slower to laod it that way line by line.
Look into the get and put statements in the MSDN you can just save a whole array with one line like put 1,,Array

now the big one (actually it's too)
instead of looping through strings and than manipulating them again to the get current one just use a two dimensional array you can declare one like this
dim Map(0 to 10, 0 to 10)... now you got an array with two dimensions that has the width and height of 11.
that makes the code much easier instead of all the string cutting you just go like
Code:
for x = 0 to 10
   for y = 0 to 10
   map(x,y)   'gives you the content of the field you want... it's kind of the same with you strings, just faster and less code like this.
  next y
next x
now you see all those case statements... It might be a way to do it but just imagine how huge your code will be when you have like 200 different tiles (if a game gets bigger that's nothing to special) well there must be some better way (it's also faster... of course )
instead of having a letter for each tile you assign a number... now you store the tiles in an array. (you can also store them in one file but it's way easier this way for now, you can easily move on after you accomplished that). When they are in an array they all got their index as their number to indentify them so now you can just go like:
draw Destination.hdc x*width,y*height,Tiles(map(x,y)).hdc

alright have a look at that..
instead of using the variable you called intX and intY I just use the x and y that where used in the foor next loop and take them times the width of the tiles.. will give you the same result 2 lines of code less and 2 variables less.
than instead of having those case statements I put what I marked Bold... the map(x,y) will return the number/index of the tile to be drawn that way one line will work for all the tiles....

I think that should help... (hey I nearly wrote a book)