am planning to make a small park bench or any kind of a bench but am not sure how I would start so I need ideas and picture?

Foor a bench I would use gumpaste - it will set up harder and support itself. Fondant might collapse - unless it's a VERY thick bench . Have you ever done a Google image search? You will get hundreds of pictures to choose from and probably find exactly what you're looking for. Good luck!!

Make it from gumpaste. Roll the paste about a quarter inch thick and use an impression mat for wood effect or a ruler and a toothpick to mark the paste the same way. Cut two rectangles, one slightly higher than the other, and leave to dry over night. Roll a sausage of paste and cut into 4 pieces for the "legs". The size depends on whatever you choose. Leave these to dry too. Turn the smallest rectangle over onto the side without the wood effect and position the legs and stick with royal icing or sugar glue. Leave to dry this way before you attach the back piece. Lay the back piece on your work top with the wood effect side facing you. Pipe a line of royal icing along the bottom to attach the seat. You will need to support this until it dries overnight or longer. I hope that makes sense to you. If not, pm me and I'll try a bit better!

another option -- see sketch.

this gives more open look.

attach slate w/ royal or gumpaste glue

could use solid slaps like aine2 does.