After searching my way through different Discussion Boards and the official AppleScript Language Guide, I came up with the following working piece of code:

tell application "Finder"
        activate
        set source_folder to choose folder with prompt "Please choose the Source-Folder:" default location ((path to home folder) as alias)
        set source_files to every file in source_folder
        set target_folder to choose folder with prompt "Please choose the Taget-Folder:" default location (":Applications:" as alias)
        repeat with i from 1 to number of items in source_files
                set source_file to (item i of source_files)
                move source_file to (target_folder) -- use "copy source_file to folder (target_folder as alias)" to copy the files
        end repeat
        set question to display dialog "Files have been moved. Move Source-Folder the trash?" buttons {"No, Thanks", "Yes, Please"} default button 2
        set answer to button returned of question
        if answer is equal to "Ja" then
                tell application "Finder" to delete source_folder
        end if
        display dialog "Files moved successfully." buttons {"OK"} default button 1
end tell

* If you want to do a copy, instead of moving the files, change the line

move source_file to (target_folder)

to

copy source_file to folder (target_folder as alias)

Sources used

• MacUser.de discussion about “Move Files using AppleScript” (DE)
• MacUser.de discussion about “Copy Files using AppleScript” (DE)
• Mac Rumors discussion about “AppleScript get list of Files”
• Apple’s official “AppleScript Language Guide”