Have done... Had done... How to use these two grammatically.

"Have done" is the present perfect tense. It is used when the action was completed recently or just now: "I have done more work today than you did all of last week."
"Had done" is the past perfect tense. It refers to something which happened earlier in the past, before another action that also took place in the past: "Before my mom came (past action) to pick me up from school, I had done (even earlier past action) almost all of my homework."
Here's more information on PRESENT PERFECT / PAST PERFECT: http://bit.ly/2KVoTs4

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