What should be my path when I want users to upload file on my website?

Depending on what you want, there are many different things that you can do in this situation.

If you want to have a single, shared image folder, in which you store the images of all users, than I recommend that you create an images directory within your projects root.

Otherwise, if you want to create a image storage that is per-user, than you can do the following:

-Project Root
    |-User 1
        |-images
        |-account
    |-User 2
        |-images
        |-account

This is a structure that contains every user in a separate folder, with the subfolders images, which contains the images for that user, and account, the storage for that user's account details and other information. This is generally more structured of a setup, and will benefit you long-term, although more advanced.

For a more scalable approach, perhaps in the future if you are willing to scale up your service, I recommend getting a large external network hard drive, or NAS (Network-attached storage), and then using that for all of the image storage. This will be very advanced, and possibly pricey, which is why it would be a long-term decision, that could quite possibly benefit your company in the future, because of the scalability.

Overall, I would generally use an images directory, regardless of the rest of the folder structure, as it is the most logically correct decision for your current situation.

EDIT: To make this setup more secure, I recommend putting the images directory into a custom, unrecognised archive file, and then converting the data when you need to use it, and back again when a change is made. This ensures no sneaky users opening your images because it is stored in a plain folder layout.