when setting up my icloud mail i accidently pressed dont merge instead of merge. can i still merge them and if i can how do i do it?

Are you sure you got a merge prompt when you set up iCloud mail? What is it you're trying to merge?

You could try going to Settings>iCloud, turning Mail to Off, then back to On again but I'm not sure you'll get another Merge prompt. If not, you would have to start over with a new iCloud account again. But I don't believe doing so will sync your iCloud account with your Yahoo email; iCloud only syncs your iCloud email. (I assume the merge option would only upload your existing email to your iCloud account, not continue to import new email from this account.)

If you want to have both accounts on your phone, just leave the Yahoo account in place. You can view both inboxes by going opening Mail, tapping the account name on the top left, then tapping All Inboxes. Or if you want to migrate to just using iCloud email, set up your Yahoo account to forward all incoming email to your iCloud address, and just use your iCloud email.

You're welcome, but just so you know, iCloud doesn't really sync email. When you check your email you are looking at it directly on iCloud's server, whether you check from your phone, your computer or any other device.

If you want to get your Yahoo email on your computer you should be able to set up your Yahoo account on whatever email program you are using on your computer. For example, if you have Windows 7 you would add the account to the Windows Mail program. Unfortunately, unless something has changed, Yahoo email is a POP email account so changes you make on your phone will not be reflected on your computer. This is only a feature supported by IMAP accounts (such as iCloud or Gmail) or Exchange accounts (such as most work email accounts).

No problem. If you sync your computer with your iCloud account, you can sync iCloud email, contacts, calendars and tasks with Outlook 2007 or higher; as well as your bookmarks with internet explorer and your photo stream photos. This will keep this data on your phone in sync with your computer. This guide shows how to set this up: http://www.apple.com/icloud/setup/pc.html.

To enable photo stream, go to Settings>iCloud on your phone and turn it on. After that, when you take a photo on your phone, the next time it is connected to wifi with the camera app closed and has at least 20% battery life remaining, it will upload the photo to photo stream and the photo will be streamed to your computer if you are syncing it with your iCloud account.

Music is only synced with iCloud if you subscribe to iTunes Match. If you do, the music in your iTunes library (up to 25,000 songs) on your computer will be made available to download to your phone over iCloud without having to sync or store it on your phone.

You can also automatically back up your device to iCloud every 24 hours when it is connected to wifi and your charger. To enable this, go to Settings>iCloud>Storage & Backup and turn it on at the bottom.

You're very welcome. To mark an answer as having helped or solved your question you just click either "This helped me" or "This solved my question" under the response that the helper posted to your question. This is overviewed here: https://discussions.apple.com/static/apple/tutorial/mark.html.