Yes, if you have i) a sound card with a subwoofer output and ii) a powered sub.
... my sub has wires like this ...
That would appear to indicate that your sub is passive (i.e., not powered). You'd need to connect your sound card's subwoofer output to a power amplifier of some sort, and then connect the sub to the speaker-level outputs of that amplifier.
send a signal? sound card? im not a professional in speakers guys, why you using fancy words and that?
The (audio) signal is the unamplified sound. Send it to an amp + speakers (or to powered speakers) and you have sound.
To get the (audio) signal out of the computer, you need a sound card. You currently have your speakers connected to one. If the sound card has a subwoofer output, you can connect a subwoofer as well. If it doesn't, you need a new sound card.