I have added more descriptions (in blue), and pics to the setup instructions found at gps.chrisb.org/UMP_Getting_Started.htm
hope this helps in your proper setup of these programs!
UMP: getting started

Keywords: GPS Garmin own homebrew map load upload loadable uploadable UMP

3. SETUP

This is the most difficult part, but it has to be done only once, so just go ahead and follow these steps:

1. Create the new directory C:\Program Files\GPSmapper

Run windows explorer
right click START then click EXPLORE

Left click at C:\Program Files see pic
Move mouse to right side of screen and right click mouse see pic
Hover mouse over NEW until another menu opens see pic then left click FOLDER
The folder is created see pic, now name it GPSmapper It should look like this now

This directory will be referred to as the program directory.

2. In it, create the new directory C:\Program Files\GPSmapper\MyData

Repeat steps above (in blue) but name MYDATA, the results should look like this

This directory will be referred to as the data directory.

(If you decide to use other names for the program and data directories, you will have to change accordingly the paths in two shortcuts installed in points 6 and 7).

3. Download the free software package:

(a) go to http://gps.chrisb.org/gps_mapper.htm;

(b) in the DOWNLOAD section, click INSTALLATION WITH RUNTIME (the latest version), download the zip file and unzip it to the program directory;
C:\Program Files\GPSmapper

c) from the program directory, run SETUP.EXE; when prompted for the directory name, enter C:\Program Files\GPSmapper (or your other program directory).

4. Create the new folder GPSmapper on your Desktop (or wherever you want). This folder will be referred to as your working folder.
Right click anywhere on the screen where NO icons are see pic then hover over NEW then left click FOLDER.
Rename to something like GPS Mapper see pic, this is the WORKING FOLDER

5. In the working folder, create a shortcut to the GPSmapper.exe program installed in the program directory.
Open the working folder (C:\WINDOWS\Desktop\GPS\GPS Mapper)
also run windows explorer and look at the program directory (C:\Program Files\GPSmapper)
re-size the windows so you can see both at the same time see pic
(right click and hold) C:\Program Files\GPSmapper and drag it to the upper window, then release it. when it is released choose "create shortcut(s) here" see pic

6. Also in the working folder, create a shortcut to the cGPSmapper.exe program installed in the program directory. In the shortcut properties dialog:
see pic

a) change the starting directory to your data directory (e.g. C:\Program Files\GPSmapper\MyData);
Right click on cGPSmapper see pic select properties

b) edit the shortcut target by adding the string ac -p at the end, so it reads as follows (provided you have the default program directory):

"C:\Program Files\GPSmapper\cGPSmapper.exe" ac -p
It should look like this see pic

7. Again in the working folder, create a shortcut to the Sendmap.exe program installed in the program directory. In the shortcut properties dialog:
see pic

a) change the starting directory to your data directory;

b) edit the shortcut target by adding the string COM1 -p at the end, so it reads as follows (provided you have the default program directory):

"C:\Program Files\GPSmapper\Sendmap.exe" COM1 -p

(if for communication with your GPS receiver you use a port other than COM1, replace COM1 with (e.g.) COM2).
It should look like this see pic

Ouffff, that's it. We've done the most difficult part. Now the fun begins.

SendMap

If you have set up sendmap and "drag and drop" the IMG files works, the screen looks like this
I am working on a Windows GUI for sendmap, here is a peek