Google can see through the 'mist':
CH340 Driver
My electronic components experience is about 15-20% but as a projects I have a very deep experience. I didn't connect them over a breadboard because they are SMD components and to save time too I just draw the schematic and ordered the board.
I made previously a board that I just connect the arduino over it but for this project I'm trying to make the arduino and the rs232 module both built in the same PCB board.
raschemmel:
A Nano uses an FT232L USB chip and requires a USB driver.
Does the CH340G require a driver and did you install it ?
Of course, if you use Mint (Linux), that becomes irrelevant. 
Hi,
Neither of the crystals in your schematic have load capacitors.
Tom... 
oops...
Should add 22pF caps from each pin to GND,
on both crystals.
I did three modifications to the circuit and finally succeed to program the chip using (upload using programmer option) BUT still when I burn the boot loader and connect the USB, the PC don't recognize the arduino to program it without using another arduino!!!
what I changed are(I marked what I changed in the schematic with a RED circle "attached"):
1- I added 1k resistor between the reset pin and 5V
2- Replaced the crystal resonator of the ch340g chip with another one (which I removed from another arduino nano which must be 12MHz as you mentioned)
3- Grounded the max3232 which it was not.
Please could you draw your suggestions over the schematic to clearly understand you.
thanks
Are those 16Mhz resonators or crystals?
I used this one for the ATmega CSTCE16M0V53-R0 Murata Electronics | C32180 - LCSC Electronics
But for the ch340g chip, I used one from another arduino nano which was for the same chip but I don't know any information about it.
Hi,
Load caps on the X2 the 340 crystal and X1 on the 328.
Note under lined items.
I would suggest you remove U4 if you have it fitted.
Tom....
If you will notice, his PCB layout already includes the footprint for the resonators quoted, which integrate the load capacitors.