で for tools/means, giving with あげます and receiving with もらいます, and もう〜ました.
で marks the tool or method used: はしで 食べます = “eat with chopsticks”.
にほんごで レポートを かきます。
I write the report in Japanese.
This で marks the instrument or means — a tool (はしで), a language (日本語で), or a method. Same particle as transport で in lesson 5.
に marks the receiver, を the gift: 友達に 花を あげます.
わたしは ともだちに はなを あげます。
I give flowers to a friend.
あげます = “give”. The receiver is marked with に, the thing given with を. あげます is used when the giver is the speaker or someone close to them.
に marks the source you receive from: 友達に 本を もらいました.
ともだちに ほんを もらいました。
I received a book from a friend.
もらいます = “receive”. The person you got it from is marked with に (から is also possible). Contrast with あげます, where に is the receiver.
もう + ました = “have already done”. “Not yet” is いいえ、まだです.
もう ひるごはんを たべましたか。…はい、もう たべました。
Have you had lunch yet? … Yes, I already have.
No, not yet.
With もう, the past ました means the action is complete. For “not yet”, don't use ませんでした (that means “didn't”) — answer いいえ、まだです.