Because WikiTree is a single world tree with exactly one profile per person, we do not do direct GEDCOM uploads. Instead, GEDCOM files are compared to what's already on WikiTree via the GEDCOMpare tool, and you can use that report to decide which of your family members to add.
Just go to the "Drop Down" menu at the top of your profile and navagation to the "My WikiTree" where there's at link to GEDCOM.
This allows you to Add & edit profiles on our shared tree using your GEDCOM. You add people one at a time after confirming or rejecting suggested matches.
One of our mentors created a tutorial for the [https://www.wikitree.com/wiki/Space:Current_GEDCOMpare_Process GEDCOMpare process] that others found very helpful. I hope that you will too.
I'll mention that you'll receive a lot of profiles to "dismiss", so if you're GEDCOM isn't in incredible condition it might be easier to input the profiles and become familiar with the WikiTree software.