It is not clear from your post, but, Windows live Mail is running successfully in PC1?
The folder you are looking for is
C:\Users\David\AppData\Local\Microsoft\Windows Live Mail
If you have installed Windows Essentials in PC2, but your concern is to also copy your previous Email data over from PC1 to PC2, then, there are two ways. Right click the folder mentioned (Windows LIve Mail) and, in the first instance, copy it to PC2 root. Then, in WLM, under File - Options - Mail - Advanced, in "Maintenance". point to the folder you have just imported. That would be, presumably c:\Windows LIve Mail.
If you now restart WLM, it should find all your previous WLM folders and Mail.
I normally keep this folder, where I have suggested. It eases the process of reinstallation etc. But, if you are satisfied with what you now see, then you can copy the same folder to its correct destination and, by the same process, redirect the "maintenance.", back to its default.
If, on the other hand, you have not yet got WLM on PC2, then it will be necessary to download it. But, a word of caution. Select the customise option and only the Mail program. The remainder are redundant in Windows 10 and can cause problems if you attempt to install them.