I recently found the Bound Sword spell, but when I want to cast it says: 'Not enough magic'.

What does this mean exactly and what do I need to improve?

Many thanks up front.

Every spell takes a certain amount of magicka to cast, your total magicka amount is probably not there yet. The perk trees have perks that reduce the cost of magicka for these spells by 1/2.

But when I attend to cast the spell my magic (blue bar) is full. Do I need to choose more Magica when I level or what?

Yeah you need more magic. or you could use clothes that reduce your magicka costs like mages robes among a few other things.

Also when you level choose the conjuration perks that reduce spell costs to half.

If you have the right equipment and perks spell casting become very easy, free in some cases.

Go to your menu and push up to view your skills. How much magicka do you have? 100? And how much does it cost to cast the Bound Sword spell?

My character is not a mage, so I probably won't have that much magica. I only wanted to use the Bound Bow, so It would not be necessary to carry a normal bow and arrows. I only use the bow against dragons and distant unnoticed enemy's.

You need to either raise your Magicka or have some 'Fortify Conjuration" so you can cast it.

I can't help you unless I know how much magicka you have lol

140/140 if thats what you mean.

Illusion: 19

Conjuration: 21

Destruction: 18

Restoration: 43

Alteration: 17

Enchanting: 60

So are you talking about Bound Sword or Bow? You should be able to cast Bound Sword right away. Bound Bow is an Adept spell though, so you need to train conjuration or put more points into magicka.

Yeah, bound sword should be do-able at this point. You'll need adept conjuration training and/or more magicka in order to use bound bow.

For example,

If you have 100 total magika and have a spell that requires 150 magika to cast, you dont have enough magika to cast it. Hence the reason for "not enough magika".

As stated you can wear robes or put enchantments on items to reduce magika cost in a particular magic school, or take the perks that cut the magika cost in half.