water pump and a jump starter

How is it behaving when you try to run the pump?
Does it turn for a few seconds?
Does it make any noise?

A jump starter has a few small batteries and a super capacitor.
It works by charging the cap for many seconds, and then dumping the energy into the starter motor.

The specs for your jump starter are specious.  
30,000 man is 30Ah, but that is not possible.
You would be lucky to get 30 amps for a few seconds.

You should get a motorcycle battery.

It turns ON. I have to hold the jump starter button for a few seconds. Also, I have a 20-gallon tank. I want to connect the pump to the tank so that I can take a shower.

Look up GT4L-BS  or  YTX4L-BS  Sport Batteries.
They are standard batteries for motorcycles and lawnmowers.
They cost between $10 and $60.
They have 3Ah energy capacity.
So the could run your 6A pump for 30 minutes.
That's maybe three showers between charges.

I don't think that the jump starter is the proper device to power anything for any length of time.  That's not its design.

d-glitch makes a good suggestion about using a motorcycle (or other) battery.  How much current does the water pump draw?

The label in the photo says 6A.

@d-glitch: you know, I hate it when someone points out that I'm being ignorant!  (especially when they are correct)

If you look at batteries (a good idea), make sure that they are sealed if the battery will ever be stored indoors.  You could get a Lithium battery, but it will cost more.  Just make sure that the battery is rated to supply a continuous 6A.  That spec may be hard to find.

Personally, I wouldn't suggest another battery.  Based on all previous questions as a whole, I would still suggest running a wire form the truck battery under the truck to the pump as I did here:
https://www.experts-exchange.com/questions/29259148/Water-Pump.html?anchorAnswerId=43531992#a43531992

Yes, there is a possibility it can drain the truck battery if run for long lengths of time BUT you would still need to recharge the motorcycle battery so since charging a battery is charging a battery, might as well put a trickle charger on the truck battery and power it from the generator.

Most of those "Jump Starters" don't work as a 12V Battery.  They only charge for a few seconds to bring your battery up to voltage momentarily and shut off.  They don't stay on.  They're typically not powerful enough if your Lead Acid battery is actually dead.

To power external appliances/devices, you probably want one of those portable power stations instead.  https://www.amazon.com/Westinghouse-Outdoor-Power-Equipment-iGen300s/dp/B08DSHCK1C/

or 

https://www.amazon.com/Portable-DLNRG-R300-Generator-Emergency/dp/B09YLBSSSJ/

Also, unless your lead acid battery is a deep cycle battery, you should not be using it to power devices long term.  Starter batteries are meant for quick, large amperage discharge and quickly charging back up.  You will severely shorten the life of your starter battery if you use it for deep cycle discharge.

How to connect the two wires with a USB?

Connect what to a USB port in what for what?

Most every USB port I've ever seen are 5 Volt output.  If you are thinking you can run a 12 Volt motor from your USB port, I would rethink that.

If you have a USB port that is outputting 12 Volts for some reason, find an old mouse/??? cut off the USB port and strip the wires back.  Look for the red and black wires.

What USB?  Those 2 power stations have a 12V "Cigarette LIghter" port, although newer cars don't come with the actual lighter "safety devices." (Yes, they were marketed as safety lighters over using a matches.)

I think we went off the tracks with the USB comment here.

I think he meant to say UPS.  
Some UPS units (but not all) include a 12V auxiliary output.