tengo un arduino uno lo acabo de comprar y cuando lo conecte a mi laptop empezó a parpadear mi led "L" no se que hacer para que deje de parpadear, ademas no me carga los programas
That's fine.
If it's groups of three flashes, that is the bootloader, running repeatedly because there's no sketch uploaded to it.
If it's a ~1s blink, that's also fine, as many vendors ship Uno clones with blink pre-loaded as an aid to debugging.