There are several methods for uploading/saving files to OneDrive for Business, including via supported web browser and the OneDrive desktop application.
PC:
If you already have OneDrive installed, uploading files from your PC is as easy as opening File Explorer, navigating to the file you'd like to upload, and dragging and dropping it into your OneDrive - University of Texas at San Antonio.
You can also save files to your OneDrive from any Microsoft product by choosing File > Save As and selecting your OneDrive - University of Texas at San Antonio
If you are using a personal PC that does not have OneDrive installed (this is very unlikely), visit portal.office.com, sign in with your UTSA credentials, and click the "Install and more" button in the top right corner.
Web Browser:
To upload files via web browser, visit portal.office.com, sign in with your UTSA credentials, and click the squares in the top left corner to find the OneDrive icon. Select it, and then click the "Add New" button in the top left. Select "Files upload" or "Folder upload" and choose your files.