Hello I can try to help you
1st make sure you have local browser open if you don't click
if you do have it then just navigate to you folder or files you want to upload
then navigate on the server browser to where you want the files/folder
Click and drag the files/folder up to the server browser window
if you have certain files/folders you want to upload press the Ctrl and left click the files/folders until you have them all keep the Ctrl key pressed when you have all the ones you want just drag them to the server browser while still holding your ctrl key when transfer starts release the Ctrl key
If you want to upload all files in a folder but not the folder go to the top of that folder in local Browser press the Shift key and scroll all the way to bottom while still holding the shift key click the last file that will select them all keep the shift key down and Drag one file over o the server ( you will see that all are being dragged ) let the shift key go when the Transfer starts