PDF pop-up window within a WP page?

I’d also like to know how to do this. My site sells clothing, and i’d like to have a popup on each garment’s product page to show measurements and such. Apparently it’s fairly easy to add a popup to any webpage, but you need access to each page’s header (or something). A whole string of code has to be added for each popup you want to include.

I’m using e-commerce, so the product page is pre-configured and I don’t know where id even go to edit the code.

Oh, and hankeester, if you just need to link to an in image, one solution is to add a picture plugin (I recommend slimbox2). Then, whenever you’re editing a page, you can select any text or picture, click on the little add link button in the editor and insert the url of the wordpress media file. Whenever something on your page is linked to an image, slimbox will open it. It would look kind of like a popup, but people would have to close it before they could look at the rest of the page again.

I considered this, but I didn’t want to have to add so much more media and set up all those links. Ideally I’d want a plugin that allows me to insert whatever text i want into a popup i could add to any part of a page.