Creative CommonsCreative Commons Licenses allow you to share your work, or use the work of others, freely - as long as you follow the license terms. Usually, you just have to:
1) Give appropriate credit
2) Provide a link to the license
3) Indicate if changes were made.
You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. Check the type of Creative Commons License before you use the material - there are several different types now, with varying restrictions.