Importing a Gedcom is a two stage process. You can search and compare people in your file with the rest of Wikitree, but your file has to be reviewed before it can be fully imported.
You will be notified when the review and full import has happened.
This is because in the past, a lot of Gedcoms have introduced low quality, or even bad, unsourced information, and take a lot of work to undo.
While you are patiently waiting, try creating a single profile manually to get a feel of things and start learning your way around.
HTH, and welcome, Chris