help me for doing that

 

4 D cells in series with a 3A silicon diode.

 

You can find lots of 5 volt power supply's at 2 amp
https://www.amazon.com/Power-Adapte...94&mcid=f9cef4236fd236c5af1e7947ccc7b6e4&th=1
These are used in things like wifi, cable boxes goodwill sales them for around a dollar. I have a hand full of these I've picked up for ESP 32 projects

 

You can also find a better 5 volt supply from Digikey, with the benefit of customer support if you need it. There is a real benefit from dealing with an actual electronic parts seller instead of mass marketer of everything.