Hello, plant them out at the backend [autumn], you can plant them up a trellis or have them scrambling through another plant, do well in full sun but i grow them in a semi shade situation and they do ok, just make sure the soil is well drained chuck some decent compost in or rotted manure, you have to cut them back to the ground in the autumn when they have died off and put some mulch over for protection, pinching the tops should increase flowering.

I have these too, and like Julien mine are only get sun for half of the day.
Next year, when the plant's settled more, it'll give you more flowers, i have a white one and it grows with 2 clematis and a climbing rose.
The proper name of your plant is Lathyrus grandiflorus or latifolius.

I'd add that if you were expecting a floral display to match the one given by the annual sweetpea, Lathyrus odoratus, you'll be disappointed - they do flower, but not so prolifically nor for so long as the annual varieties. Pick your planting spot carefully - once in the ground, they're next to impossible to dig out and move again, the roots seem to go down to Australia... I always think they look best left to climb up large shrubs - used to grow mine up a purple leaved Cotinus, when the flowers could be seen to full advantage.