First: Go to Settings, Style Configurator, Change the Global Styles, Default Style's background color to the color settings at the following picture
http://imgur.com/zwwa8iL
 
Next: Copy the following code from this paste, to a file named "GreentextStyle.xml"
 
<NotepadPlus>
    <UserLang name="Greentext (Def)" ext="" udlVersion="2.1">
        <Settings>
            <Global caseIgnored="no" allowFoldOfComments="no" foldCompact="no" forcePureLC="0" decimalSeparator="0" />
            <Prefix Keywords1="no" Keywords2="no" Keywords3="no" Keywords4="no" Keywords5="no" Keywords6="no" Keywords7="no" Keywords8="no" />
        </Settings>
        <KeywordLists>
            <Keywords name="Comments">00&gt; 01 02 03[spoiler] 04[/spoiler]</Keywords>
            <Keywords name="Numbers, prefix1"></Keywords>
            <Keywords name="Numbers, prefix2"></Keywords>
            <Keywords name="Numbers, extras1"></Keywords>
            <Keywords name="Numbers, extras2"></Keywords>
            <Keywords name="Numbers, suffix1"></Keywords>
            <Keywords name="Numbers, suffix2"></Keywords>
            <Keywords name="Numbers, range"></Keywords>
            <Keywords name="Operators1"></Keywords>
            <Keywords name="Operators2"></Keywords>
            <Keywords name="Folders in code1, open"></Keywords>
            <Keywords name="Folders in code1, middle"></Keywords>
            <Keywords name="Folders in code1, close"></Keywords>
            <Keywords name="Folders in code2, open"></Keywords>
            <Keywords name="Folders in code2, middle"></Keywords>
            <Keywords name="Folders in code2, close"></Keywords>
            <Keywords name="Folders in comment, open"></Keywords>
            <Keywords name="Folders in comment, middle"></Keywords>
            <Keywords name="Folders in comment, close"></Keywords>
            <Keywords name="Keywords1"></Keywords>
            <Keywords name="Keywords2"></Keywords>
            <Keywords name="Keywords3"></Keywords>
            <Keywords name="Keywords4"></Keywords>
            <Keywords name="Keywords5"></Keywords>
            <Keywords name="Keywords6"></Keywords>
            <Keywords name="Keywords7"></Keywords>
            <Keywords name="Keywords8"></Keywords>
            <Keywords name="Delimiters"></Keywords>
        </KeywordLists>
        <Styles>
            <WordsStyle name="DEFAULT" fgColor="000000" bgColor="D2DBFF" fontStyle="0" nesting="0" />
            <WordsStyle name="COMMENTS" fgColor="A7A7A7" bgColor="000000" fontStyle="0" nesting="0" />
            <WordsStyle name="LINE COMMENTS" fgColor="00801E" bgColor="D2DBFF" fontStyle="0" nesting="0" />
            <WordsStyle name="NUMBERS" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="KEYWORDS1" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="KEYWORDS2" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="KEYWORDS3" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="KEYWORDS4" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="KEYWORDS5" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="KEYWORDS6" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="KEYWORDS7" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="KEYWORDS8" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="OPERATORS" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="FOLDER IN CODE1" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="FOLDER IN CODE2" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="FOLDER IN COMMENT" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="DELIMITERS1" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="DELIMITERS2" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="DELIMITERS3" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="DELIMITERS4" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="DELIMITERS5" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="DELIMITERS6" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="DELIMITERS7" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
            <WordsStyle name="DELIMITERS8" fgColor="000000" bgColor="FFFFFF" fontStyle="0" nesting="0" />
        </Styles>
    </UserLang>
</NotepadPlus>
 
 
Lastly: In Notepad++ go to Language, Define Your Language. Click on the Import button and choose your newly created GreentextStyle.xml File.
 
Viola! Your Notepad++ Should look like this.
>Maybe.
[spoiler] If you are lucky. [/spoiler]
 
Note that the green is not 100% perfect and the spoiler text is not 100% white for readability reasons.