Welcome to WikiTree! You can find your GEDmatches report here:
You can also always find it under the "Changes" tab at the top of your profile.
The next step is to follow the directions on the report to review the Suggested Matches and either mark them as a match or reject them, skip individuals missing a birth or death date, etc. Once you've done that you can click the long, grey Approve button down towards the bottom of the page and your GEDCOM will be submitted for review.
If you have any questions, feel free to send me a message. Thanks!