if i have a reentry pass what do i have to do to leave Thailand and return?

i all ready had 2covid shots(Pfizer)

I did it twice in 2021.  Since you have a reentry permit that is Step #1 of a long list.  In terms actually leaving Thailand you only an airline ticket and meet the Covid 19 Testing requirements for your destination and possibly the transit country.  Then follow the steps necessary to obtain the Thailand Pass through the Thai Embassy or Consulate in your destination country.  Good luck and give yourself enough time to get things done.