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The balance left on the card will come from new charges. Pay your statement balance by the due date or sooner. When statement time approaches, if your new charges for the month are higher than what you'd like to see reported, make a payment to bring your balance down least $5 but not much more. When the statement cuts, pay the $5. Charge as usual, and bring the balance down again when it's time for another statement.
The other card should report a balance of zero. To do that, pay the balance to zero before the statement cuts.
The amount of the credit builder loan does not matter. Mine is $500.
I would check with some local Credit unions, or if you have a Military affiliation, you could try NFCU.
I'd definitely get that CO paid, and try to get PFD. Otherwise it's going to be there for a while and contribute to holding your score down, for a while.
You might want to add a second CC, like Discover Secured. Trying to increase your score with just one card is going to be difficult.
I would also suggest checking out the "Rebuilding Your Credit" section for additional tips/help etc.