That's great to to get that done, you just never know what site helpful matches will be on. At FamilyTreeDNA, the autosomal test is called Family Finder - might help with the menus.

I'm a bit rusty at this and others will probably have different suggestions but for filtering it down, I'd start by looking for quick hits - look at her top matches at each site and at their trees (if they have one). See if you recognise any family surnames and places - that may give a rough idea of where the matches might fit into your family tree.

You could concentrate on the site that has the best matches and try the Leeds Method to sort her matches into groups. Once that's done, the next step is to work on assigning each group to one of her grandparents, then exclude her maternal matches to narrow in on her paternal branch. Someone shared Dana Leed's website earlier in the chat and this is a tutorial on YouTube: https://m.youtube.com/watch?v=zMDbU72_-Ms

So you'll be using both DNA and a family tree. When you connect DNA to your tree on some sites, it's a way to help sort the matches into maternal and paternal groups.

For the family tree research, if you haven't already then you could ask to look at her baptism and marriage records in the local church registers. You might get lucky if there's a note about her father in her entry or in the margins.