see free space

hello, i am new here, i am trying to learn arduino, i want to see free space in the my arduino board can anybody help me?

Do you mean:

SRAM?
EEPROM?
Flash?

As far as SRAM, there is a library somewhere.

As for flash, it says when you compile your program.

And EEPROM...just know how many addresses you have used out of the max.

how can i to erase everything?

You can write a sketch to erase EEPROM

Then upload this sketch:

void setup()
{
}
void loop()
{
}

That gets rid of most things (~530 left for bootloader and main() )

When you compile and load a program, the information that you are asking for is displayed at the bottom of the IDE window.