In this short blog tutorial I will explain how to give items Attribute Modifiers.
Now if you don't know what these are, then they are basically attributes that will take effect when you wear or
hold the item with the attribute.
The following attributes are for the player and mobs.
generic.movementSpeed
generic.maxHealth
generic.attackDamage
generic.knockbackResistance
generic.followRange

The following are for Horses.
horse.jumpStrength

The following are for Zombies.
zombie.spawnReinforcements

Now here's an example on the command your going to use.

/give @p 301 1 0 {AttributeModifier:[{AttributeName:"generic.movementSpeed",Name:"generic.movementSpeed",Amount:0.5,Operation:0,UUIDLeast:8000,UUIDMost:4000}]}

If you used this command you will know that this will give you leather boots with a Speed attribute of 0.5

This is not very hard to do all you need to do is memorize on how to write the command.
The attributes listed above are all self-explanatory
If you still don't understand go to this link:http://www.planetminecraft.com/project/item-attribute-template-with-command/
This link will lead you to my Template world about this topic it will contain a item template and a command block template.