How to add product customizations and attachments in PrestaShop
From the product settings of your PrestaShop store you can make it possible for customers to customize a product, and you can also attach files that customers can download from the product page.
To offer customizations, log in to the backend of your store, click on the Catalog tab, open the edit screen for the particular product and from the tabs with the product settings select Customization. On the page that opens you'll see two settings: File fields and Text fields.
The first option is for offering customers the possibility to upload an image, and the second to type a text. If you want customers to be able to upload an image, type the digit 1 in the field for File fields and click on the Update settings button. Another field will appear in which you can type some text that will be displayed on the product page of the frontend, just below the image upload field. You can also make the field a required one by marking the respective checkbox. Then click on the Save labels button to save the settings.
The Text fields setting works in the same way. If you want more image or text fields to be displayed on the frontend, simply type the corresponding number in the fields for File fields and Text fields.
On the product edit screen of the admin panel the tab next to Customization is Attachments. From the options of that tab you can attach files that customers will be able to download from the product page of your store's frontend. After you click on the tab, type the name of the file and a description in the respective fields, and use the Browse button to locate the file on your local computer. Click on the button Add a new attachment file.
The file will be displayed in the textarea under Available attachments. To offer the file for downloading, select it and click on the Add button. Then click on the Update attachments button in the bottom left corner of the page. Now customers will be able to download the file from the product page. To delete attachments or edit their options go to Catalog tab>Attachments sub-tab (this is a different Attachments tab).
For screenshots and some more details you can also read the tutorial on adding product customizations and attachments in PrestaShop.