Hey ! Of course, let me clarify it for you ;)
First let's conjugate the verb MANGER at the present form.
• Je mange = I eat
• Tu manges = You eat
• Il mange = He eats
• Nous mangeons = We eat
• Vous mangez = You eat
• Ils mangent = They eat
When you want to say : "You eat an orange" --> "Tu manges une orange" (the article is "une" because orange is "feminine")
When you want to say : "We eat an orange" --> "Nous mangeons du riz" (Never write "de le", "du" replaces "de le", but you were right because you can't put the article "un" or "une" because "riz" is uncountable. It also occurs in English so it makes sense ;))
Now yeah there is in fact a subtlety with the "vous". In French, when you want to adress to someone with polite manners (examples : an older person, your teacher, a stranger,...), you will use "vous" instead of "tu". And "vous" remains "vous", you will always conjugate a "polite vous" the way you conjugate a "normal vous (all of you)".
Let's take an example, you meet a stranger in the street, you want to say "Hi, how are you ?" (I know it's an out-of-reality situation :D), in French you can say : "Bonjour, comment allez-vous?". That is be the polite form. The more familiar form would be : "Bonjour, comment vas-tu?". Quick reminder : the verb ALLER is conjugated like this :
Je vais = I go
Tu vas = You go
Il va = He goes
Nous allons = We go
Vous allez = You go
Ils vont = They go
I hope it makes sense now :)) If you have any other question, feel free to ask ^^