As you can see, you can select from Stage 1 to Stage 5 on the top, just by clicking them. Stage 1 is currently selected.

Below it, you can select the phase. As an LF2 player you of course know that enemies don't come all at once in stage mode. Instead, they come in groups. A phase consist of a group of enemies coming at once.
The five colors represents phases in Stage 1-1, 1-2, 1-3, 1-4 and 1-5 (or 2-1, 2-2... etc)
I am not sure what happens if you put four phases in for example stage 4-2, which should only be 2 phases. This program follows the one used in the original stage file.

Below it there are three rows of that black things.
The one on the top contains the enemies coming from the right side of the screen while the one on the bottom from the left side.
The middle one contains milk bottles which will appear when the phase starts. It will later be updated to contain criminals and beer as well.
I call this middle one the 'Field Box'. This box simulates the stage in gameplay so if you put the milk on the left, it will appear on the left as well.

The scroll bar and text on the right is the Bound, i.e. the size of the playable field when you play the stage, which is automatically set to a default of 900-1300-1700-2200 (3000) value (nearly exactly the same as the original stage.dat)

The bottom-most things are the most important ones:
The Unit Pallete - You can add enemy units by clicking on the unit you wish to add. To speed things up, you can use the hot keys shown on the left-top of each unit.
The Code Generator - After filling phases with units, you want to get the code. Check the stages you have worked on and click on Generate Code. The code will appear in the white box (okay I will remove that 'RichTextBox1' text in the next update. I just forgot to)

It might be confusing so I'm explaining that man. He is the third in the top-most row. Okay, he is Bandit/Hunter. If you add him to your stage, then one of either Bandit or Hunter will come in the Stage Mode.

Also notice that the left-bottom character IS NOT template (lol) . He is meant to represent id: 1000, which means a random hero character (chars you can choose in LF2 without typing lf2.net, other than template (lol again) )

I know, Deep & LouisEX looks weird, but really, nothing's happened to them ^^ . In fact their weapon doesn't fit in the 60x80 frame :\

To remove all units in a phase, you can double click the enemy unit boxes (the black boxes).

To remove a unit, right-click on the Unit Pallete, or hold Ctrl while pressing the hotkey.

Adding units - simply clicking or pressing the hot keys will add the unit to the top box (coming from the right).
To add enemy units to the bottom box (coming from the left), hold Shift while clicking or pressing the hot keys. You can also remove units coming from the left by holding Shift+Ctrl and press the hot key.

To add milk, simply click on the Field Box. To add more, keep clicking :B .
And hey, right click on the Field Box if you want to remove the milk.

I don't know how to write to *.dat, neither do I am willing to learn it (just because it looks hard. if it's easy, please tell me ) .
So you still need the LF2 Data Changer.
1. Open 'stage.dat' with LF2 Data Changer (stage.dat can be found in <YOUR LF2 DIRECTORY>\data\stage.dat)
2. Replace the whole stage with your code. In case you only create for Stage 2, scroll down and find something like "<stage> id: 10 #stage 2-1" - then delete all of the Stage 2 and replace with your new code.
3. You are good to go, except if my programs still have bugs .