ذي - ذات - ذا- ذو ... all are used in (formal) speeches . and have the same meaning . they mean ( have ) ... you can also use the words (صاحب ) or (لديه ) instead of them to give the same meanings . anyways here are some examples : Ex: كل تلميذ متفوق في الدراسة يكون ذا أخلاق حسنة Ex: مصر دولة ذو حضارة عريقة Ex: تسلق احمد الشجرة ذات الأفرع العالية Ex: كل ذي علم يستطيع ان ينفع وطنه

firstly : i think you meant (write ) instead of (white) ..
me too , i also started again learning English , but this time i use a dictionary ( Longman ) , i try to summarize it . which defines words in English so i read all explanations and examples . that helps me increasing my reading skills as well .
I've been following this way since 3 years , i just study at my free time " not every day at all haha "
in addition chatting with foreign friends is so important " native or non native speakers " no matter
Good luck ^_^

باللغة العربية الفصحى : اشتاق اليكم وباللهجة المصرية العامية : وحشتونى

و عليكم السلام حين و حينما ..both mean when but very very formal words " i personally don't use them at all haha " عندما .. literally means when . لمّا .. is the most popular one and means when also . " but notice that's very informal word ,so don't use it in writing documents , letters or .... etc " the summary ( just use لمّا and عندما ) عندما is more formal . I'll say an example once in standard Arabic and other in slang or informal Arabic as we talk in daily life standard : انا استيقظ من النوم عندما تشرق الشمس informal : انا بصحي من النوم لما الشمس تطلع another example ... standard : لا استطيع ان اسافر الا عندما أنهى دراستى اولاً informal : مش هقدر اسافر الا لمّا اخلص دراستى الاول