I have used this technique several times. but it is always different from time to time and where the dent are. but here is what I did.

clean the dent area, with alcohol, white sprite etc..

have the glue gun hot and ready.

take a new glue stick and place a lot of hot glue in the middle of the dent and attach the unused stick and let it sit for at least 15 min...

try then to pull the dent out with the glue stick.

remove the glue and stick with a hair dryer

you may have to do this several times if the dent is big or you did not pulled it correctly.

as stated you should always wash and polish the dent area after.

Hope this was any help