raised beds

Hi Mary, welcome to GOY.
The best place for you to purchase wood for your project is from your local fencing company. I would say buy three, eight ft. gravel boards. 8x1ft. tanelised soft wood, cut one in half and with some small pieces of 2x2ins. for the corners, you can make up a frame 8x4ft.
You need a membrane for the base, take off some of your topsoil, put in the membrane, place your frame on top, fill up to 9ins. with your own topsoil, plus compost, sharp sand. You may have to buy in some more soil. As soon as this is settled you should be reay to plant up.
Hope this helps.

We used some spare decking boards to make our raised bed which we call the allotment! It's 8' long by 2' wide , 10" deep, and has been used to grow many veggies. The base is 12" from the ground (good for avoiding backache!) on legs made from 2" x 2" timber. Check out my pics for idea. Just filled with multi purpose compost (quite a few bags as it's so big!). Then we painted the outside with fence paint to match the other bits in the garden.

thanks for your replies,very much appreciated