From there, the Upgrade button should be on the top right. If, for some reason it isn’t, you can go to your Team settings (your team name with the gear icon on the left of the Dashboard) → Change Plan → and Upgrade from there.
From there, the Upgrade button should be on the top right. If, for some reason it isn’t, you can go to your Team settings (your team name with the gear icon on the left of the Dashboard) → Change Plan → and Upgrade from there.