I hate to make a long story short so lets expand on this a little.
I grew up with highly pixelated images, The Number Munchers game, and well before Google. If you need answers you went to go get them. As in physically leaving the house to go get them.
Since we have all of resources at our fingertips i'll highlight some of the best sources that may come up during your google search.
The best way to find disassembly and reassembly instructions are to first search by the model and brand of mobile device, laptop or ultrabook that you own. If you have a Dell Ultrabook it's best to do a search using both dell and ultrabook disassembly and reassembly as keywords. This will give you a more narrowed down search that is specific to your kind of device. If you do a generic search it will give you instructions for their device which may not apply to yours.
If you are a visual person you can even watch YouTube tutorials to see how others have disassembled and reassembled thier device or even follow along with them. Here's a screenshot of a video on YouTube that shows the disassembly of a Dell Ultrabook:
To complete the process with less errors, I recommend using YouTube because it is easier to follow the instructions.
Ifixit gives detailed step by step instructions on disassembling a Dell Ultrabook along with pictures like the one seen above from their website. Ifixit and other similar websites are excellent ways to find disassembly and reassembly instructions for laptop, Ultrabook and mobile device repair. If you prefer to not watch or cannot access the video, this method works just as fine. This method and YouTube are highly recommended for users that have little to no experience in this process.