I want to adjust patterns sizes, can I do it with my own patterns?

I just found this site and there is a lot to learn for sure, just wondering if you can use your own patterns or only the ones they have listed? I can never find patterns that fit me so I’d love to be able to use this site to adjust the measurements but the pattern selection isn’t what I’m looking for and I have my own patterns I just need the measurements adjusted

Site works only with the listed patterns.