Go on line with a question such as 'how to build a wooden arch' lots of plans, photos and instructions come up on how to make one, from plain ones to quite grand or Gothic ones. Good luck with it.

Here's one I built about 10 years ago. i've added some sizes and details but they're estimates from memory

http://www.flickr.com/photos/31559373@N00/4031438909/in/set-72157594380287112

Here's a similar one with a different design I found on the web which would be simple to build

http://www.herbgardendesign.co.uk/wp-content/uploads/2012/05/Wooden-Garden-Arch.jpg

Thank you both. I was searching rose arch!! Anyway hopefully I can put the instructions into practice and achiieve an arch!

I am sure you can Geoff good luck. I found with arches the wider the better for getting through with things like wheelbarrows etc. Also I have seen the posts put in to 'Metpost' and hammered in to stop rotting and so much digging out.

I've noticed in my local park that several of the arches have galvanised steel square section steel ( about 1 inch square ) set into concrete and protruding 6 inches out of the ground. The vertical wooded posts of the arch are then attached to these with a gap of about an inch between the bottom of the post and the ground.

Treated occasionally those posts will never rot