Internal sound cards are more expensive and produce better sound, but are really only needed for higher end setups with more than just 2 speakers, or high end studio headphones. I'd recommend doing a bit of research on them to see which one will fit your needs the most based on your budget and the needed specs (refer to your desired headset to see what it's max audio quality is compared to your motherboard, things like min/max frequency, bit rate, kHz, etc). It has separate headphone and mic ports, and comes with its own audio driver software to control frequencies, bass strength, separate audio in/out, etc. For reference, I use the Creative Sound Blaster Play 3, which was around $20. There are plenty of cheap external USB sound cards that can plug into any USB port (I use mine on a front USB port as all my rear ones are taken up), and often can produce better audio quality than the motherboard alone will provide. The solution to this is to get a sound card, either internal or external, as they will come with additional audio ports.
Sound card jacks are often color coded pink, blue and. Ideally your case would come with front panel audio/mic in ports, however if it does not, you will have to use either the headphones or the speakers in that port, but not both. You will commonly find three round jacks, the size of a headphone jack, on the back of a desktop computer. Yes, both would need the line-out (lime) port for audio.
