trying to load my iCloud account to my mac mail

having a hard time launching my iCloud account to my mac book on the mail the little bird icon. I did my update on my lap top

and i had my two accounts active yahoo and iCloud now only my yahoo works but my iCloud is inactive. It's frustrating!! how do

i activate my iCloud. Also my IM is not active either! was before. but everything works well on my iPhone.