Write simple Installer for Windows application

Need a very simple installer using Nullsoft Install System. Goal: Copy 3 files into specific folder and delete another one if exists. Pseudo code 1) main_path = Read one registry key (result is a directory) 2) search_path = main_path + "subdir A" (subdir name known) 3) find all directories right below search_path filter those matching number schema like 8.2, 8.3, 8.4, 9.1, 9.2 found_dir = pick the one with the highest number (in example above 9.2) 4) install_dir = search_path + found_dir 5) copy 3 files into install_dir ... files specified via File /r "C:\location_of_files\*" (so automaitcally done anyway) 6) check_file = install_dir + some_specific_subfolders + file_name check if check_file exists, if that is the case, remove that 7) create unistaller under programs that will delete the 3 files copied It should be realtively straight forward.