If Yesware isn't displayed in Gmail, you'll want to make sure it's installed and enabled.
For Chrome Users: Open up a new browser tab and type chrome://extensions into the address bar to check if Yesware is installed and enabled.
For Firefox Users: Click on 'Tools' then 'Add-Ons' and choose the 'Extensions' tab to check if Yesware is installed and enabled.
Next, try reloading Gmail.
Finally, check if the Yesware menu is present. You should find it in the top right of Gmail. If it is present, click 'Activate' and you'll be prompted to sync your Gmail account.