After deciding to take his dog for a walk in the forest, he finds himself with a wooden box that possesses a powerful ring, but there is someone else, who wants the power.

That is definitely better Forrest. You could even get more specific if you wanted. Instead of White-collar man you could say Banker or Stockbroker in order to give more description to the reader.

Hope that helped, good luck with this!

Thank you for you kind words. I have updated it to "After finding a powerful ring, a white-collar man must keep the magical relic from a greedy other dimensional man in order to save the world."

Since so much needs to be said in a logline, it's important to know what to cut and what to keep.

Fore-instance, I would cut "After deciding to take his dog for a walk in the forest," Since going on a walk doesn't sound important to the story.

I would also cut "he finds himself with a wooden box," because the ring's important, not what material the box is made of.

-After finding a powerful ring-

Next you should give us a glimpse of the main character, You simply refer to him as "He"

How about, -A gruff woodsman-

Next you should do the same for the Antagonist. You simply refer to him as "Someone Else"

How about, -A greedy Wizard-

Now you should tell us what the hero needs to "Do"

-He must protect the ring in order to save the world-

Now let's try to put this together, maybe make a few small changes and see what comes up.
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"After finding a powerful ring, a gruff woodsman must keep the magical relic from a greedy wizard in order to save the world."
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Your logline can be different of course, it might not be a 'Gruff Woodsman' but a 'Lonely Baker' but hopefully you see how I put this together.

I have, good guy, his goal or what he needs to do, who or what is standing in his way and what the stakes are.

Hope this helped. Good luck with this!