You are asking quite a few different questions here, without giving too much detail. I'll try to give some guidance, but without a lot more detail, it's hard to be specific.
First, the question doesn't have anything to do with WinForms, what you are asking would be the same in pretty much any approach, so I'll ignore WinForms.
If you have the template in a database table, presumably as plain text (which could of course be HTML, PostScript or any other markup language) with placeholders, and you have the data in another table, then you can simply merge the two together to produce the CV in plain text.
Once you have the merged CV, converting it to PDF is best done with a library. It's not the sort of thing you want to try doing yourself. Which library you use depends a lot on your requirements and budget. There are one or two free ones, but I can't say how good they are, as I use a commercial one. I'm not making any specific recommendations here, but a bit of searching and experimenting should get you what you want.
Hope that answers you questions. If not, please edit your question to include more specific information.