Circumventing Open File Dialog Box when Uploading a file to a website

Hello board,

I am a brand new member here, and I am nearly brand new to coding. I cut my teeth using uBot Studio, if anyone is familiar with that. So I have a pretty basic understanding of coding and scraping specifically. I'm trying to recreate a bot for my business that I built in uBot using either vb.net or c#. Vb.net seems to be what I'm the most comfortable with so far, but I'm open-minded to switching if necessary. So here's what I'm having an issue with specifically:

My application navigates to a website. It logs in to my account. It goes to a specific item I have in my account after scraping and manipulating some data to set the file name to upload, then it needs to upload a file based on that data. This is where I am having the problem.

I can get the program to click the "upload files" button, but if I do that, an open file dialog box pops up. I need to be able to change the file field without the dialog box opening. I know this is possible, as I've built this bot already using uBot, and the "change file field" command did exactly what I want this to do. I am not sure what uBot is coded in though, so it may not be possible in vb.net but it is in some other coding language at least. If that's the case, I will need help with that language.

Any help here would be greatly appreciated.