I uploaded a pic to be used as my profile picture, however, it doesn't appear on any of my posts. Is this like the "signature" thing where you have to have a certain number of posts & days as a member before you can have a profile picture??

You can and do have it A profile pic appears on your profile page and your photo is showing up there. An avatar is the one that appears on your posts, so you'll need to upload one there as well.

I'm sorry for any confusion. It's very common to confuse the two and I wish they were worded a little better in the UserCP

Thanks for the help Suzanne!