[1.19.2] Send package to server whit 2 int values if posible adding an specific itemstack

Good days
Im working to make a way soo i can hold left click and behave like hold right click but doing an different action 

i find and old video form mi mod in 1.8  this is one of the things i would like to accomplish 
in this case the gun shoots by holding right click 

and the chainsaw works by holding left click 

minecraft ticks are a little unconstant sometimes there's lag and damage calculations soo to more or less precisely calculate how mutch time the player has hold and release the left click button i need two values 
int ontime = 0;

int offtime = 0;

this values only happens in the client side soo i need to send those values back to serverside 

i been following kapenhoe tutorials but he don't show how to actually serialize and send values 

im pretty sure thats done in this to methods 

	public ExampleC2SPacket(FriendlyByteBuf buf) {
	}
	public void toBytes(FriendlyByteBuf buf) {
	}
	

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in this case i need to send values to an item capability soo if is possible to specifies the itemstack in the package it would be just perfect 

something like 

public ExampleC2SPacket(ItemStack mark) {

FriendlyByteBuf buf = mark.getcapability.serializeallthevaluesinsidethecapability();

send_to_server(buf)

}

public void toBytes(FriendlyByteBuf buf) {

Itemstack mark = itemsendedfromtheclientside;

mark.getcapability.deserializethisvalues(buff);

}

this is the spefic tutorial i benn follow 

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well i need a guidance on how to send values using packages and also the itemstack if its possible

thanks for your time