Hello and welcome to the forum!
The coin identification and evaluation part of the forum is here:
https://en.numista.com/forum/forum12.html , just please keep in mind pictures are needed to determine the exact coin and value, Gustaf VI Adolf was the king of Sweden and there are many coins minted during his reign.
As for selling you don't qualify yet to sell on the site, please check the sell rules here:
https://en.numista.com/forum/topic22085.html I collect and deal in ancient Roman coin. In case you're looking for affordable ancient coins or need any help with the coins you already have send me a message.