What do you mean 'drag in a txt file'?
I hope your not dragging and dropping the txt file onto the exe.
This is what you should be doing :
Find a .bmp file.
Drag and drop the .bmp file onto bmp2script.exe.
Put the .txt file it makes in blockland/config/client/macros
Open blockland, join a server, open macro saver, and load the macro.