Spain uses the European standard 230 volt, 50 Hz power. It also uses the European-standard two-round-pins outlets. You will need an adapter to change the shape of the plug. You can buy these online (Amazon, Monoprice, etc) or at local big box stores - Best Buy, Target, Walmart, etc.
Look at your power adapters. Each one has a small label (maybe engraved directly on the plastic) that says something like INPUT: xxxx. If it says "INPUT: 100-240 volts, 50/60Hz" then all you need is an adapter to change the shape of the plug. 99% of all electronics made in the last 10 years fall in this category.
If the label indicates that it only takes 120 volt input, then you'll need a transformer to adjust the electricity to 120 volts, 60 Hz from the European 230 volts, 50 Hz. I would be shocked (pun intended) if you need this for any electronics you bring over there.
http://www.power-plugs-sockets.com/spain/
I have one like this:
https://www.amazon.com/Grounded-Univ...travel+adapter
I also have a kit like this, which has adapters for most countries you'd visit:
https://www.amazon.com/International...ectric+adapter
You can also buy an all-in-one adapter like this:
http://www.monoprice.com/product?p_id=9876
If your laptop cord has a grounding pin, then it's best to buy an adapter with a usable grounding connector.
Either works just fine.
edit: I also renamed the thread for clarity.