I think your location may be playing its part, as I guess it gets a lot warmer in your part of the world relative to the typical " English Rose" growing here in the UK.

Having said that with the right variety and aftercare you should get reasonable results.

Particulary if you get your soil (dirt) fertile with plenty of humus dug in, and you never allow the soil to dry out!

Have a look here at some pictures and aftercare tips and you should get some success!

http://www.thegardenersalmanac.co.uk/Data/Rose/Roses.htm

If, by one layered, you mean you only get one flush of flowers and that's it, it's probably the variety of rose you have. Some (usually ramblers) flower for about 4-6 weeks and that's it. Other 'bush' roses (HT/Floribunda) may have a gap or pause between flowerings.

Or do you mean you have only one layer of petals, in which case you simply have a single variety and you want a double one.

thank you!!!!