How does AE-L work on the Nikon D7000?

Ok, I have no issues with manually and auto focusing when talking photos of another subject, however, when setting my camera on a tripod and using the self-timer remote I don't understand how to keep my photos sharp. Took over 50 shots and all 50 were either blurry or really soft. Using different apertures, some headshots other full. I read the nikon d7000 handbook on the AE-L and AE-F features and attempted to use it to "lock" my focus and recompose my picture (namely myself) but once I hit the remote and hear the shutter open and close, I'm disappointed by a soft image. I really don't understand how to focus, either man or in auto, maintain that focus, and then take the photo of myself seeing as how I'm not behind the camera to press the shutter button halfway down… Someone please help me grasp a little more so I can go back outside and try again… I can take great photos of other folks but suck at taking them of myself!

You're overthinking.

Get a stick or something, focus on that. Now switch camera to manual focus and take the shot with the timer.

The AEL and AEF and not going to be of much help.

You need to first of all set a smaller aperture so you will have much more depth of field and focus precision will not be as critical. Set the aperture to f11 or even f16

Then you need to MANUALLY focus on an object placed where you will be in the photo. One you have this focus achieved, you can remove the object and replace it with… You!

There's another method that can also work well. Again, set a smallish aperture. Set up your tripod, then take the camera off the tripod and carry it to where you will be in the photo. Pose just as you are going to in the photo. Use the camera to MANUALLY focus on the head of the tripod. Then go mount the camera back on the head of the tripod.

These methods will usually give you a shot in focus, but it is still not foolproof. Even when you get a sharp photo, the composition is not likely to be perfect. It will take more trial and error to get that correct, or just crop the photo in Photoshop as needed to get the composition you want.

Of course, all this is also assuming you have MANUALLY set the exposure into the camera. Best to get your exposure readings from a grey card placed in the area where you will be posing.